Answer: TRUE
Explanation: INTEGRATION MANAGEMENT is one of the ten PROJECT MANAGEMENT BODY OF KNOWLEDGE (PMBOK) guide knowledge area can be defined as coordinating responsibilities,resources(financial or non-financial), stakeholders(project team and end users) and any other project aspects. Integration management also involves conflicts resolution between different units of a project, making prudent and best decision between competing activities or needs and analysing the resources available to ensure that it meets the required specifications.
A projectile is launched at a diagonal angle and is in the air for 17.5 seconds. How long does it take the projectile to reach its apex?
Answer:
[tex]t_h=8.75\ s[/tex]
Explanation:
For a projectile the total time it stays in the air is called the flight time. The path traced during a projectile motion is parabolic with symmetry of time and distance.
Given that the projectile having a flight time of 17.5 seconds, will reach the top point in half of the flight time taken by it:
So, [tex]t_h=\frac{T}{2}[/tex]
[tex]t_h=\frac{17.5}{2}[/tex]
[tex]t_h=8.75\ s[/tex] is the time by the end of which the projectile will be at its apex having the vertical component of velocity as zero.
Do note that during a projectile analysis we neglect the air resistance due to which we have a constant horizontal component of the velocity and the vertical component of the velocity varies under the influence of gravity. The vertical velocity at the top becomes zero.
A department store sells an ""astronomical telescope"" with an objective lens of 30 cm focal length and an eyepiece lens of focal length 5 mm. What is the magnifying power of this telescope?
Answer:
The magnifying power of this telescope is (-60).
Explanation:
Given that,
The focal length of the objective lens of an astronomical telescope, [tex]f_o=30\ cm[/tex]
The focal length of the eyepiece lens of an astronomical telescope, [tex]f_e=5\ mm=0.5\ cm[/tex]
To find,
The magnifying power of this telescope.
Solution,
The ratio of focal length of the objective lens to the focal length of the eyepiece lens is called magnifying of the lens. It is given by :
[tex]m=\dfrac{-f_o}{f_e}[/tex]
[tex]m=\dfrac{-30}{0.5}[/tex]
m = -60
So, the magnifying power of this telescope is 60. Therefore, this is the required solution.
One type of slingshot can be made from a length of rope and a leather pocket for holding the stone. The stone can be thrown by whirling it rapidly in a horizontal circle and releasing it at the right moment. Such a slingshot is used to throw a stone from the edge of a cliff, the point of release being 18.0 m above the base of the cliff. The stone lands on the ground below the cliff at a point X. The horizontal distance of point X from the base of the cliff (directly beneath the point of release) is thirty times the radius of the circle on which the stone is whirled. Determine the angular speed of the stone at the moment of release.
Answer:
15.66 rad/s
Explanation:
The vertical motion and horizontal motion are independent of each other.
t = √ ( 2 s/ g) where t = time for the ball to reach the ground and s is the height of the cliff = 18.0 m
t = √ ( 36 / 9.81 ) = 1.916 secs
horizontal distance travel = ut where u is the horizontal velocity of the stone = 30 × r (radius)
tangential velocity V = angular velocity ( ω) × radius
distance traveled = ω × r × t = 30 × r
radius cancelled on both side
ω = 30 / 1.9156 = 15.66 rad/s
Why is thermal energy from the Sun transferred to Earth through electromagnetic waves instead of any other type of thermal energy transfer?
Answer:
Because electromagnetic waves can travel through empty space
Explanation:
The energy that is emitted from the sun is transferred to the earth in the form of radioactive waves. These waves are originated due to the vibration between the electric and magnetic fields. As this energy reaches the earth, it warms the earth's atmosphere, resulting in the transfer of heat energy in three possible ways namely the conduction, convection, and radiation.
This electromagnetic waves do not require any matter for the transmission of energy, and can easily travel in empty space from the core of the sun to the earth and other nearby planets. Whereas other types of waves cannot travel in space, so it is transferred in the form of electromagnetic waves only.
Answer:
The electromagnetic waves can pass through empty space.
Explanation:
Earth continually moves about 30 km/s through space, which means the wall you stand next to also is moving at 30 km/s. When you jump vertically the wall doesn't slam into you because ________
Answer:
we are on the same frame of reference moving with the earth with the same velocity.
Explanation:
Given that the earth is continuously moving at a speed of about 30 kilometers per second in the space. This means this is the observed speed from and external frame of reference in space being at rest.But when we jump from vertically on the earth we are already on the same moving frame of reference and bounded to it by the gravity and hence when we jump off its surface we jump with its velocity of motion and so does every other object present on the earth and hence we do not collide with the wall when taking a vertical jump beside it. To us the wall seems to be at rest because we both are on the same frame of the reference.A wire carrying a 32.0 A current passes between the poles of a strong magnet such that the wire is perpendicular to the magnet's field, and there is a 2.15 N force on the 3.00 cm of wire in the field. What is the average field strength (in T) between the poles of the magnet?
Answer:
2.24 T
Explanation:
From Electromagnetic Field,
F = BILsin∅................ Equation 1
Where F = Force on the wire, B = Field strength, I = current flowing in the conductor, L = length of the conductor, ∅ = The angle the conductor makes with the magnetic field.
Making B the subject of the equation,
B = F/ILsin∅..................... Equation 2
Given: F = 2.15 N, I = 32 A, L = 3.00 cm = 0.03 m, ∅ = 90° ( the wire is perpendicular to the magnetic field)
Substitute into equation 2
B = 2.15/(32×0.03×sin90°)
B = 2.15/0.96
B = 2.24 T.
Hence the Field strength = 2.24 T
Quaternary structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids.True or False.
Answer:
False: Quaternary structure is achieved when multiple polypeptide chains in protein come together.
Explanation:
There are four levels of protein structure: primary, secondary, tertiary, and Quaternary structure.
Tertiary structure is a protein structure, which is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids.
However, Quaternary structure is achieved when multiple polypeptide chains in protein come together.
What is the speed of a car going v=1.000 mph in SI units? Notice that you will need to change miles to meters and from hours to seconds. you can do each conversion separately. Use the facts that 1 mile=1609 m and 1 hour= 3600s
Answer: The speed is 0.4694 m/s.
Explanation:
S.I or M.K.S system has seven fundamental units which are used to find derived units
1) Mass - Kilogram
2) Length - meter
3) Time - Seconds
4) Electric Current - Ampere
5) Amount of substance - Moles
6) Intensity of light - Candela
7) Temperature - Kelvin
The conversion used from miles to feet is:
1 mile = 1609 m
1.000 miles= [tex]\frac{1690}{1}\times 1.000=1690m[/tex]
The conversion used from hour to sec is:
1 hr = 3600 sec
We are asked: 1.000 miles/hr = ? m/s
[tex]1.000miles/hr=\frac{1690}{3600}m/sec=0.4694m/sec[/tex]
Therefore, the speed in SI unit is 0.4694
Match the characteristic or descriptive phrase to the type of application it describes.
Part A
a. sound waves
b. soft-tissue imaging
c. electromagnetic wave
d. fetal imaging
Part B
1. ultra sound
2. mri
Answer:
Sound waves and fetal imaging is related to the ultrasound.
Electromagnetic wave and soft tissue imaging is related to the MRI.
Explanation:
Ultrasound scans is basically a process in which high frequency sound waves are used for the fetal imaging or examining the internal organs like liver, kidneys etc. It's the safe procedure as no radiations are involved in this case.
However the MRI stands for Magnetic resonance imaging that use the electromagnetic waves and is best for the soft tissue imaging etc.
Sound waves and electromagnetic waves are key to ultrasound and MRI imaging. Ultrasound uses sound waves for applications like fetal imaging, while MRI uses electromagnetic waves for soft-tissue imaging.
Explanation:To match the characteristic or descriptive phrase to the type of application it describes:
a. sound waves - 1. ultrasoundb. soft-tissue imaging - 2. MRIc. electromagnetic wave - 2. MRId. fetal imaging - 1. ultrasoundUltrasound is a medical imaging technique that uses high-frequency sound waves to create images of the inside of the body. It is particularly useful for fetal imaging during pregnancy as it is non-invasive and safe for both the mother and fetus. On the other hand, Magnetic Resonance Imaging (MRI) uses electromagnetic waves in the radio-frequency range to create detailed images of the body's soft tissues, making it invaluable for detecting conditions within the body's interior.
An observer sees a flower pot sail up and then back down past a window 2.45 m high. If the total time the pot is in the sight is 1 s, what is the height above the window up to which the pot rises?
Answer: 2.55meter
Explanation: Using the second equation of motion.
S{hieght} = U*t + {g*t²}/2
Where U is initial velocity =0m/s
g is acceleration due to gravity 10m/s²
t is time 1secs
So we have,
hieght = 0 + {g*t²}/2
hieght = {10*(1)²}/2
Total hieght travelled is 10/2
Which is 5 meter.
But we are asked to find the hieght above the window which as a hieght of 2.45meter.
So,
hieght above window would be
{5 - 2.45}meter
Which is 2.55 meter.
The standard used by LEED in the Water Efficiency (WE) category to determine the baseline case for building water usage is the national standard for maximum flush and flow rates called:
Answer:
EPAct of 1992.
Explanation:
The Energy Policy Act (EPAct) is a United States Of America government act passed in the year 1992 and became effective in October 24, 1992.
The Energy Policy Act was established to address the energy needs in the United States of America by amending laws to increase and provide incentives for clean and renewable energy and also to decrease the dependence on imported energy.
Find the voltage change when (a) an electric field does 12 J of work on a 0.0001-C charge and (b) the same electric field does 24 J of work on a 0.0002-C charge.
Answer:
a. [tex]Change in Voltage=12*10^{4}V[/tex]
b. [tex]Change in Voltage=12*10^{4}V[/tex]
Explanation:
The work done in moving an electric charge round a circuit is express as
[tex]workdone=voltage*charge \\Wd=v*q[/tex]
The voltage is in-turn define as the electric potential energy per unit charge.
[tex]Voltage=\frac{potitntial energy }{charge}\\[/tex]
a. for a 12J work done on a charge of value 0.0001C, we can compute the voltage change as
[tex]Voltage=\frac{potitntial energy }{charge}\\Voltage=\frac{12J}{0.0001C}\\ Voltage=12,0000J/C\\ Change in Voltage=12*10^{4}V[/tex]
a. for a 24J work done on a charge of value 0.0002C, we can compute the voltage change as
[tex]Voltage=\frac{potitntial energy }{charge}\\Voltage=\frac{24J}{0.0002C}\\ Voltage=12,0000J/C\\Change in Voltage=12*10^{4}V[/tex]
The voltage change in (a) is 1.2 × 10⁵ J/C and in (b) is 1.2 × 10⁵ J/C.
a) Based on the given information,
• Work done (W) is 12 J and charge (q) is 0.0001 C.
The change in voltage is determined by using the formula,
= W/q
Now putting the values we get,
= [tex]\frac{12}{0.0001} J/C[/tex] or 1.2 × 10⁵J/C
b) Based on the given information,
• Work done (W) is 24J and charge (q) is 0.0002 C.
The change in voltage can be calculated as,
= W/q
Putting the values we get,
=[tex]\frac{24}{0.0002} J/C[/tex] or 1.2 × 10⁵J/C
Thus, the voltage change in both the conditions is 1.2 × 10⁵J/C.
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A 0.145-kg baseball pitched horizontally at 27.0 m/s strikes a bat and pops straight up to a height of 31.5 m. If the contact time between bat and ball is 2.5 ms, calculate the average force between the ball and bat during contact.
The average force between the ball and the bat during the contact is 1,566 N.
The given parameters;
mass of the ball, m = 0.145 kghorizontal velocity of the ball, u = 27 m/sheight of the ball's displacement, h = 31.5 mthe contact time of the ball, t = 2.5 msThe average force between the ball and the bat during the contact is determined by applying Newton's second law of motion.
F = ma
where;
a is the acceleration of the ballm is the mass of the ballThe average force is calculated as follows;
[tex]F = ma = m\frac{v}{t} \\\\F = \frac{mv}{t} \\\\F = \frac{0.145 \times 27}{2.5 \times 10^{-3}} \\\\F = 1,566 \ N[/tex]
Thus, the average force between the ball and the bat during the contact is 1,566 N.
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To calculate the average force between the ball and bat during contact, you first calculate the speed the ball leaves the bat using the gravitational potential energy formula. Find the change in velocity, then use the formula for force using this change in velocity and the given time.
Explanation:The subject of this question is physics, specifically involving the concepts of force, mass, speed, and time. This problem first requires using the equation for gravitational potential energy to find the speed at which the ball leaves the bat. That is Potential energy = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height. This will give you the final speed of the baseball after the contact with the bat.
Next, find the change in velocity (or 'delta v') by subtracting the initial speed of the baseball from its final speed. The average force can then be calculated using Newton's second law transformed in impulse form: Force = delta p / delta t = m * delta v / delta t, where delta p is the change in momentum, delta v is the change in speed, and delta t is the change in time.
This calculation should provide the answer to your question, and requires understanding of physics concepts such as gravitational potential energy, impulse, and force.
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Lord Kelvin's calculations for dating the earth were correct, but his assumption that earth was undergoing radiant cooling from combustion of the sun was incorrect, thus he arrived at an incorrect age of 15-20 million years old.
a) true
b) false
Answer:GiGi
Explanation:
A solid metal ball and a hollow plastic ball of the same external radius are released from rest in a large vacuum chamber. When each has fallen 1 m, they both have the same?
Answer:
time of fall and the final velocity
Explanation:
the mass of solid ball is more than the mass of hollow ball.
According to the third equation of motion
v² = u² + 2gh
As the final velocity v does not depend on the mass of the object, so the final velocity of both the ball is same.
According to the first equation of motion
v = u + gt
As v is same for both the balls, the time is also same for both the balls.
So, they both have same time of fall and final velocity.
An athlete at the gym holds a 3.0 kg steel ball in his hand. His arm is 78 cm long and has a mass of 3.8 kg, with the center of mass at 40% of the arm length from the shoulder. What is the magnitude of the torque about his shoulder due to the ball and the weight of his arm if he holds his arm.
a. Straight out to his side, parallel to the floor?
b. Straight, but 45° below horizontal?
Answer:
a. 34.6 Nm
b.24.4 Nm
Explanation:
a.
78 cm = 0.78 m
W = F =mg
m1 = mass of steel ball = 3 kg
m2 = mass of long arm = 3.8 kg
moment due to steel ball = Fd =(m1*g)*(0.78)= (3*9.81)(0.78)=22.95 = 23 Nm
moment due to arm =Fd=(m2*g)*(0.78*0.4)= (3.8*9.81)(0.312)=11.63 = 11.6 Nm
net moment = 23 +11.6 = 34.6 Nm
b. now in this the angle will change the perpendicular moment arm
moment due to steel ball = (3*9.81)*(0.78cos45) = 16.23 =16.2 Nm
moment due to arm = (3.8*9.81)(0.4*0.78cos45) = 8.22 = 8.2 Nm
net moment = 16.2 +8.2 = 24.4Nm
(a) The magnitude of the torque about his shoulder due to the ball and the weight of his arm parallel to the floor is 34.55 Nm.
(b) The magnitude of the torque about his shoulder due to the ball and the weight of his arm straight, but 45° below horizontal is 24.43 Nm.
The given parameters;
mass of the ball, m = 3.0 kglength of the arm, L = 78 cm = 0.78 mmass of his arm, = 3.8 kgA sketch of the position of the ball and the arm;
---------------------------------------------------------------------------78cm
↓ 40% ↓
3 kg 3.8 kg
Take moment about the arm;
The moment due to arm (clockwise), is calculated as follows;
M₁ = Fd = (3.8 x 9.8) x (0.4 x 0.78) = 11.62 Nm
The moment due to ball (clockwise), is calculated as follows;
M₂ = Fd = (3 x 9.8) x (1 x 0.78) = 22.93 Nm
The magnitude of the torque about his shoulder due to the ball and the weight of his arm parallel to the floor is calculated as;
τ = M₁ + M₂
τ = 11.62 + 22.93 = 34.55 Nm
(b) The moment at angle 45⁰ below the horizontal is calculated as follows;
The moment due to arm (clockwise), is calculated as follows;
M₁ = Fd = (3.8 x 9.8) x (0.4 x 0.78) x (cos45) = 8.22 Nm
The moment due to ball (clockwise), is calculated as follows;
M₂ = Fd = (3 x 9.8) x (1 x 0.78) x cos(45) = 16.21 Nm
The magnitude of the torque about his shoulder due to the ball and the weight of his arm straight, but 45° below horizontal is calculated as;
τ = M₁ + M₂
τ = 8.22 + 16.21
τ = 24.43 Nm.
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A catapult launches a boulder with an upward velocity of 92 m/s. The height of the boulder, h, in meters after t seconds is given by the function h = –5t2+ 92t + 16. How long does it take to reach maximum height? What is the boulder’s maximum height? Round to the nearest hundredth, if necessary. A. Reaches a maximum height of 16.00 meters in 18.4 seconds. B. Reaches a maximum height of 18.57 meters in 9.2 seconds. C. Reaches a maximum height of 37.14 meters in 18.4 seconds. D. Reaches a maximum height of 439.20 meters in 9.2 seconds.
Answer:
D. Reaches a maximum height of 439.20 meters in 9.2 seconds.
Explanation:
Given
h = –5t²+ 92t + 16
then
h' = 0 when the boulder reaches its maximum height
(–5t²+ 92t + 16)' = - 10t + 92 = 0
⇒ t = 92/10
⇒ t = 9.2 s
the maximum height will be
h = –5(9.2)²+ 92(9.2) + 16
h = 439.20 m
A 38.0 kg child is in a swing that is attached to ropes 1.70 m long. The acceleration of gravity is 9.81 m/s 2 . Find the gravitational potential energy associated with the child relative to the child’s lowest position under the following conditions:
Answer:
at zero point : GPE = 0 J
at max height : GPE = 633.7 J
Explanation:
the gravitational potential energy at the lowest point is zero
maximum height relative to the lowest point = h =1.70 m
G potential energy at max height = mgh = (38kg)(9.81m/s^2)(1.7)
= 633.7 J
What is the ratio of the electrical force to the gravitational force between an electron and a positron?
Answer:
Explanation:
mass of electron = 1.9 ×[tex]10^{-31} kg[/tex]
mass of proton = 1.67 ×[tex]10^{-27}[/tex][tex]kg[/tex]
Gravitational Force = [tex]F_{g}[/tex] = [tex]\frac{Gm_{p}m_{e} }{r^{2} }[/tex] = [tex]\frac{6.67 * 9.1* 1.67*10^{-69} }{r^{2} }[/tex]
Electrostatic Force = [tex]F_{E}[/tex] = [tex]\frac{1}{4\pi epsilon} \frac{e^{2} }{r^{2} }[/tex] = [tex]\frac{9*10^{9}* 1.6*1.6* }{r^{2} }[/tex]×[tex]10^{-38}[/tex]
[tex]\frac{F_{g} }{F_{E} }[/tex] = [tex]4.47[/tex]×[tex]10^{-40}[/tex]
a bucket filled with water has a weight of 150 N and is attached to a rope that is woud around a pully (solid disc) with a 0.5m radius and a mass of 15kg. I fthe bucket is allowed to fall, what will the angular acceleration of the pulley ?
Answer:
20 rad/s^{2}
Explanation:
weight / force (F) = 150 N
radius (r) = 0.5 m
mass (m) = 15 kg
angular acceleration = tangential acceleration / radius
where
tangential acceleration = force/ mass = 150/15 = 10 m/s^{2}substituting the above into the equation for angular acceleration we haveangular acceleration = 10 / 0.5 = [tex]20 rad/s^{2}[/tex]
A set of facts and relationships between facts that can explain and predict related phenomena is called a(n) ____.a. theoryb. experimentc. descriptive methodd. hypothesis
Answer:
a. theory
Explanation:
A scientific theory is a set of facts and rules, that is, scientific laws, which express relationships between observations of these facts. Therefore it is a set of principles to explain a certain type of natural phenomena. Thus, the strength of a scientific theory is related to the diversity of phenomena it can explain and its simplicity.
Final answer:
A set of facts and relationships that can explain and predict phenomena is known as a theory, which is a well-supported scientific explanation and the foundation of scientific knowledge.
Explanation:
A set of facts and relationships between facts that can explain and predict related phenomena is called a theory. A theory is a well-supported explanation of observations and is often used as the foundation of scientific knowledge. It goes beyond a hypothesis, which is a tentative explanation that can be tested, by being supported by a substantial amount of empirical evidence and experimentation. In contrast to a theory, a law summarizes the relationships between variables without explaining why they occur.
The process of discovery in science usually follows the scientific method, where hypotheses are made and then tested through experiments and observation to acquire new knowledge.
The speed of a nerve impulse in the human body is about 100 m/s. If you accidentally stub your toe in the dark, estimate the time it takes the nerve impulse to travel to your brain.
problem is worked out down below in an attachment
Final answer:
It takes approximately 0.015 seconds for a nerve impulse from a stubbed toe to reach the brain, calculated based on the speed of the nerve impulse (100 m/s) and the estimated distance (1.5 meters).
Explanation:
To calculate the time it takes for a nerve impulse to travel from a stubbed toe to the brain, we need to consider the speed of the nerve impulse and the distance it must travel. The speed of a nerve impulse is about 100 m/s. Assuming an average distance from the toe to the brain via the spinal cord is approximately 1.5 meters (taking into account the height of an individual and that nerve paths are not completely straight), we can use the formula:
Time = Distance / Speed
Plugging in the values gives us:
Time = 1.5 m / 100 m/s = 0.015 seconds.
So, it takes approximately 0.015 seconds for a nerve impulse from a stubbed toe to reach the brain. This rapid transmission allows the body to respond quickly to stimuli, protecting it from further injury.
A stone initially moving at 8.0 m/s on a level surface comes to rest due to friction after it travels 11 m. What is the coefficient of kinetic friction between the stone and the surface?
Answer:
Coefficient of friction will be 0.296
Explanation:
We have given initial speed of the stone u = 8 m /sec
It comes to rest so final speed v = 0 m /sec
Distance traveled before coming to rest s = 11 m
According to third equation of motion
[tex]v^2=u^2+2as[/tex]
So [tex]0^2=8^2+2\times a\times 11[/tex]
[tex]a=\frac{-64}{22}=-2.90m/sec^2[/tex]
Acceleration due to gravity [tex]g=9.8m/sec^2[/tex]
We know that acceleration is given by
[tex]a=\mu g[/tex]
So [tex]2.90=9.8\times \mu \\[/tex]
[tex]\mu =\frac{2.9}{9.8}=0.296[/tex]
So coefficient of friction will be 0.296
To calculate the coefficient of kinetic friction, we first use Newton's second law to calculate the force of friction. Then, we divide that force by the normal force, yielding our coefficient.
Explanation:To find the coefficient of kinetic friction, you'll need to use the formula for kinetic friction (f = μkN), where 'f' is the force of friction, 'μk' is the coefficient of kinetic friction, and 'N' is the normal force. In this case, the force of friction can be found by using Newton's second law (f = ma), where 'm' is the mass of the stone and 'a' is its acceleration. The stone's acceleration can be found using the formula a = (vf - vi)/t, where 'vf' is the final velocity (0 m/s, since the stone comes to rest), 'vi' is the initial velocity (8.0 m/s), and 't' is the time it takes for the stone to stop. Once you've found the force of friction and the normal force (which is equal to the weight of the stone, or mg, where 'g' is the acceleration due to gravity), you can solve for the coefficient of kinetic friction.
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Joe and Max shake hands and say goodbye. Joe walks east 0.50 km to a coffee shop, and Max flags a cab and rides north 3.45 km to a bookstore. How far apart are their destinations?
Answer:
3.486 km
Explanation:
Suppose Joe and Max's directions are perfectly perpendicular (east vs north). We can calculate their distance at the destinations using Pythagorean theorem:
[tex]s = \sqrt{J^2 + M^2}[/tex]
where J = 0.5 km and M= 3.45 km are the distances between Joe and Max to their original parting point, respectively. s is the distance between them.
[tex]s = \sqrt{0.5^2 + 3.45^2} = \sqrt{12.1525} = 3.486 km [/tex]
A student standing on the ground throws a ball straight up. The ball leaves the student's hand with a speed of 16.0 when the hand is 1.80 above the ground.How long is the ball in the air before it hits the ground? (The student moves her hand out of the way.)
There are mistakes in the question as the unit of speed and height is not mention here.The correct question is here
A student standing on the ground throws a ball straight up. The ball leaves the student's hand with a speed of 16.0m/s when the hand is 1.80m above the ground.How long is the ball in the air before it hits the ground? (The student moves her hand out of the way.)
Answer:
t=3.37s
Explanation:
Given Data
As we have taken hand at origin and positive upward
So given data are
[tex]y_{i}=0m\\y_{f}=-1.80m\\v_{i}=16.0m/s\\a=g=9.8m/s^{2}[/tex]
To find
time taken by the ball before it hits the ground
Solution
By using the common kinematic equation
[tex]y_{f}=y_{i}+v_{i}t+0.5at^{2}[/tex]
Put the given values and find for t
So
[tex]-1.80=0+16.0t+(0.5*(-9.8)t^{2} )\\-1.80=16.0t-4.9t^{2}\\ 4.9t^{2}-16.0t-1.80=0[/tex]
Apply quadratic formula to solve for t
[tex]t=\frac{-(-16.0)+\sqrt{(-16)^{2}+4(4.9)(-1.80)} }{2(4.9)}\\ t=3.37s[/tex]
Gina walks 3 mph for 4 hrs. How far did she walk? 1.3 mi 7 mi 0.75 mi 12 mi
Answer: [tex]12 mi[/tex]
Explanation:
Velocity [tex]V[/tex] is mathematically defined as:
[tex]V=\frac{d}{t}[/tex] (1)
Where:
[tex]V=3 \frac{mi}{h}[/tex] is Gina's velocity
[tex]t=4 h[/tex] is the time Gina spends walking
[tex]d[/tex] is the distance Gina has walked
Isolating [tex]d[/tex] from (1):
[tex]d=Vt[/tex] (2)
[tex]d=(3 \frac{mi}{h})(4 h)[/tex] (3)
Finally:
[tex]d=12 mi[/tex] This is the distance Gina has walked
You drive on Interstate 10 from San Antonio to Houston, half the time at 72 km/h and the other half at 98 km/h. On the way back you travel half the distance at 72 km/h and the other half at 98 km/h. What is your average speed (a) from San Antonio to Houston, (b) from Houston back to San Antonio, and (c) for the entire trip?
Answer: a. 85km/hr b.82.3km/hr
c. 84km/hr
Explanation: first let take the total time from San Antonio to Houston to be 2hr.
Half time 1hr was covered with speed of 72km/hr
Distance = speed*time=72km/hr *1hr
=72km
So too with the second half of 1hr covered with speed of 98km/hr
Distance = 98km
Total distance from Houston to San Antonio is 98+72 =170km
a. Average speed from San Antonio to Houston is
S1 =170/2
=85km/hr
b.half distance from Houston to San Antonio which is 170km/2
= 85km was covered with speed of 72km/hr first half, so time
t = dist/speed
t = 85/72 = 1hr 12 mins
Remaining 85 km covered with a speed of 98km/hr
Time = 85/98 = 0.88*60min
= 52 mins
Total time = 1hr +12mins +52mins
=2hr4mins= 124/60 hr
So average speed = distance/time
=170/124/60
Using reciprocal law
Average speed S2= 170*60/124
= 82.3km/hr
C. Average speed to and fro(entire tripe)
= (85+82.3)/2
=84km/hr
A jet plane is cruising at 300 m/s when suddenly the pilot turns the engines up to full throttle. After traveling 4.0 km, the jet is moving with a speed of 400 m/s.
What is the jet's acceleration, assuming it to be a constant acceleration?
I got :
a =
8.8
m/s2
Is your answer reasonable? Explain.
Explanation:
We have equation of motion v² = u² + 2as
Initial velocity, u = 300 m/s
Acceleration, a = ?
Final velocity, v = 400 m/s
Displacement,s = 4 km = 4000 m
Substituting
v² = u² + 2as
400² = 300² + 2 x a x 4000
a = 8.75 m/s² = 8.8 m/s²
The acceleration is 8.8 m/s²
The answer got is reasonable.
Final answer:
The jet's acceleration, assuming it to be a constant acceleration, is 8.75 m/s². The initial calculation of 8.8 m/s² was close, but using the kinematic equation we find the precise acceleration value.
Explanation:
Let's calculate the jet's acceleration with the given information. We know the initial speed (u), the final speed (v), and the distance (s) covered during acceleration:
Initial speed, u = 300 m/sFinal speed, v = 400 m/sDistance covered, s = 4.0 km or 4000 mWe can use the kinematic equation:
v² = u² + 2as
Where:
v is the final velocityu is the initial velocitya is the accelerations is the distancePlugging in the values:
4002 = 3002 + 2a(4000)
Solving for a gives:
a = (400² - 300²) / (2 × 4000)
a = (160000 - 90000) / 8000
a = 70000 / 8000
a = 8.75 m/s²
Your computation of 8.8 m/s² is quite close but let's ensure we're using the correct figures. The actual acceleration is 8.75 m/s² when calculated correctly, so a slight revision may be needed on your calculation depending on your rounding during the process.
Car drag racing takes place over a distance of a 1 4 mile (402 m) from a standing start. If a car (mass 1500 kg) would be propelled forward with a pulling force equal to that of gravity, what would be the change in kinetic energy and the terminal speed of the car (in mph) at the end of the race be?
Answer:
The change in kinetic energy is 5,909,400J and the terminal speed of the car is 160,800mph
Explanation:
Change in kinetic energy = mg(h2 - h1)
Mass (m) = 1500kg, g = 9.8m/s^2, final distance (h2) = 402m, initial distance (h1) = 0m
Change in kinetic energy = 1500×9.8×(402 - 0) = 1500×9.8×402 = 5,909,400J
From equations of motion
h = ut + 1/2gt^2 [u is initial speed and is equal to zero because the car drag racing began from a standing start (rest)]
h = 1/2gt^2
402 = 1/2 × 9.8t^2
402 = 4.9t^2
t^2 = 402/4.9 = 82.04
t = √82.04 = 9.06s × 1h/3600s = 0.0025h
Terminal speed = distance/time = 402m/0.0025h = 160,800mph
The ____ method of assessing intake is time consuming, and the results may not be accurate if subjects modify their eating habits during the time of the study.
Answer:
Food record
Explanation:
A food record method is an assessment, study or act of collecting data related to food.
Although Food record method is time consuming and may not be accurate if subjects modify their eating habits during the time of the study the data collected here are of great importance. Some of the importance are;
(1). It helps in the registration of foods.
(2). The data can be used to describe a population's intake.
(3). The data can be used as a reference parameter in validation studies.
(4). The data can also be used with the Food Frequency Questionnaire.
It other disadvantage apart from its time consuming and error that might occur during the process of conducting the research is that it might be burdensome to the respondents.