A river has a steady speed of 0.500 m/s. a student swims upstream a distance of 1.00 km and swims back to the starting point. (a) if the student can swim at a speed of 1.20 m/s in still water, how long does the trip take? (b) how much time is required in still water for the same length swim? (c) intuitively, why does the swim take lon- ger when there is a current?
Final answer:
The round trip swimming in the river with a current takes a total of 2016.8 seconds, while the same trip in still water would take 1666.7 seconds. The additional time required when there is a current is because the effective speed of the swimmer is reduced when going against the current, which outweighs the time saved by the increased speed when going with the current.
Explanation:
A river has a steady speed of 0.500 m/s and a student swims upstream a distance of 1.00 km and swims back to the starting point. Given these conditions, we can calculate the time taken for the entire trip, the time required for a similar trip in still water, and understand why swimming in a current takes longer.
Part A: Time for the round trip with current
Upstream, the student's effective speed is 0.70 m/s (1.20 m/s - 0.500 m/s) since the current opposes the swimmer. Downstream, the effective speed is 1.70 m/s (1.20 m/s + 0.500 m/s) as the current aids the swimmer. To find the time, we use the formula time = distance / speed. Thus, the time taken upstream is 1428.6 seconds and downstream is 588.2 seconds. The total time for the round trip is 2016.8 seconds.
Part B: Time for the same swim in still water
In still water, where there is no current, the speed of the swimmer is 1.20 m/s. The total distance of 2.00 km (1.00 km upstream and 1.00 km downstream) would require 1666.7 seconds to swim, calculated using the same distance/speed formula.
Part C: Intuition behind increased time with current
Intuitively, when there is a current, the effective speed of the swimmer decreases when swimming upstream because the current opposes the swimmer's motion, and although it increases when swimming downstream, the overall effect is that more time is needed to complete the swim as compared to swimming in still water. This is due to the fact that the loss of speed when going against the current has a more significant impact on the total time than the gain in speed when going with the current.
A crazy dog runs 300 meters east, changes his mind and then runs 200 meters west. He then changes his mind again and runs 500 meters east. This entire trip takes 2 minutes. a) what is the total distance traveled? b) What is the total displacement? c) What was the dog’s average speed? d) What was the dog’s average velocity?
Answer:
Distance 1000 meters
Displacement: 600 meters east.
Average speed: 500 meters per minute
Average velocity: 300 meters per minute
Explanation:
In order to calculate this you just have to know the difference between distance and displacement, distance is the total meters that someone walk or run or moved accros, and displacement is a vector, that is the result of how far away from the starting point the object finished. Then with this two values you can calculate average speed which is distance between time, and average velocity which is displacement between time.
A wave has the wavelength equal to 396 nm. what must be the frequency of this wave
Put each event in order of its occurrence, according to the big bang theory. please note that more accurate calculations of the age of each event are still actively being researched, so there is some variability in estimations that you might find on the internet. a few seconds after the big bang ~800 million years after the big bang ~9 billion years after the big bang ~1 billion years after the big bang
a. formation of hydrogen and helium atoms
b. formation of large nebulae into protostars and eventually full blown stars
c. early massive stars exploded producing supernovae and heavier elements
d. formation of our sun and the earth
Final answer:
The chronological order of events according to the Big Bang theory begins with the formation of hydrogen and helium atoms a few seconds after the Big Bang, followed by the formation of protostars and stars around 400 to 500 million years later. Subsequent events include the creation of heavier elements through supernova explosions, culminating in the formation of our Sun and the Earth about 9 billion years after the Big Bang.
Explanation:
To put each event in order of its occurrence according to the Big Bang theory, we can use our knowledge of cosmic history and the timelines provided by theoretical predictions and observational evidence to create a chronological list.
Formation of hydrogen and helium atoms - This event occurs a few seconds after the Big Bang, when the universe was extremely hot and dense, allowing for the creation of protons, neutrons, and eventually leading to the formation of hydrogen and helium nuclei.
Formation of large nebulae into protostars and eventually full-blown stars - About 400 to 500 million years after the Big Bang, the universe had expanded and cooled enough for the first stars and galaxies to begin forming from large clouds of gas.
Early massive stars exploded producing supernovae and heavier elements - This process of star formation and destruction, including supernovae, would have begun relatively soon after the first stars formed and continued throughout the history of the universe, enriching the interstellar medium with heavier elements over time.
Formation of our Sun and the Earth - Our solar system, including the Sun and Earth, formed about 9 billion years after the Big Bang, from the gravitational collapse of a region within a large molecular cloud.
Two cars are driving on a straight section of the interstate in opposite directions with 70 mph. They are one mile apart.
a) They have the same velocity.
b) They have the same speed.
c) None of the above.
I don't understand this question. Please some one explain to me!
Which of the following correctly compares gravitational force and distance between two objects?
As the distance increases, the gravitational force increases.
As the distance increases, the gravitational force decreases.
As the distance decreases, the gravitational force decreases.
There is no relationship between gravitational force and distance between two objects.
Answer:
[force hope this help]
Explanation:
Spaceship 1 and spaceship 2 have equal masses of 300 kg. spaceship 1 has an initial momentum magnitude of 600 kg-m/s. what is its initial speed?
Explanation :
Given that,
Mass of the spaceship 1, m = 300 kg
Initial momentum of the spaceship 1, p = 600 kgm/s
Momentum is the product of the mass and the velocity with which it is moving i.e.
p = m v
[tex]v=\dfrac{p}{m}[/tex]
[tex]v=\dfrac{600\ kgm/s}{300\ kg}[/tex]
[tex]v=2\ m/s[/tex]
The initial velocity of the spaceship 1 is 2 m/s.
Hence, this is the required solution.
Final answer:
To find the initial speed of spaceship 1 with a momentum of 600 kg-m/s and mass of 300 kg, one should use the momentum formula (momentum = mass * velocity) and solve for velocity, resulting in an initial speed of 2 m/s.
Explanation:
To calculate the initial speed of spaceship 1 with a given momentum, we need the formula for momentum, which is the product of mass and velocity (p = m * v). Since we have the mass (m = 300 kg) and the momentum (p = 600 kg-m/s), we can solve for the initial speed (v) of spaceship 1 by rearranging the formula to v = p / m.
Doing the calculation gives us v = 600 kg-m/s / 300 kg, which results in v = 2 m/s. Therefore, the initial speed of spaceship 1 is 2 meters per second.
The early earth was much cooler than it is today.
a. True
b. False
you touch a downed power line covered or bare, what’s the likely outcome?
Answer:
The likely result is that you die due to a strong discharge of electricity.
Explanation:
Electricity goes its way to the cities through a high voltage grid. Traveling over hundreds of kilometers of wire, electric power is very dangerous and can cause shock as a result of an electric shock that can kill any living thing. Falling, covered or empty power lines are very dangerous and should not be touched under any circumstances. These lines can contain high voltage energy and cause death if touched by someone who is not properly protected, so it can only be touched by professionals with proper protective equipment.
A person leaves a house and walks three blocks north, then walks three blocks west. In what direction is the displacement of the person, relative to the starting point? A North B Northwest C South D Southwest
A girl pulls a sled with a force of 15 N over a distance of 3 m. What is the kinetic energy of the sled after she pulls it? Assume there is no friction.
Answer:
Kinetic energy, KE = 45 J
Explanation:
It is given that,
Force applied by girl on a sled, F = 15 N
It moves a distance, d = 3 m
We need to find the kinetic energy of the sled after she pulls it. We know that the work done is equal to the change in kinetic energy
[tex]W=\Delta E=K_f-K_i[/tex]
[tex]K_i=0[/tex] (initial at rest)
[tex]KE=W=F\times d[/tex]
[tex]KE=15\ N\times 3\ m=45\ J[/tex]
So, the kinetic energy of the sled after she pulls it is 45 J. Hence, this is the required solution.
How is a scientific law unlike a scientific theory?
Answer:
Both scientific law and theory are the scientific statements related to any natural phenomenon.
Both are the proved hypothesis but they differ as a scientific law tells how a natural phenomenon takes place whereas a theory explains why the natural phenomenon takes place.
A scientific law cannot be changed but a theory can be modified and changed when new evidence comes into existence.
Thus, both are different.
An alpha particle is also referred to as a nucleus of which isotope? lithium-7 helium-4 hydrogen-2 helium-2
Answer: Option (b) is the correct answer.
Explanation:
A positively charged particle that consists of two protons and two neutrons is known as an alpha particle.
The symbol for alpha particle is [tex]^{4}_{2}\alpha[/tex]. An alpha particle is similar to a helium atom because helium atom also has mass number (number of protons + number of neutrons) as 4 and atomic number (number of protons) as 2.
Symbol of helium atom is [tex]^{4}_{2}He[/tex].
Thus, we can conclude that an alpha particle is also referred to as a nucleus of helium isotope.
suppose larry stands with more weight on one scale than the other if one scale reads 400 N. what does the other read?
You will take 400N divide by 2. The answer will be 200N.
A large box is being pushed by three separate people. The first person is pushing the box at a rate of 6 m/s directly north. The second person is pushing the box at a rate of 6 m/s directly to the northeast. The third person is pushing the box at a rate of 6 m/s directly east. Determine the magnitude and direct of the resultant vector of he box.
How far is the rocket from the launch pad 6.70 s later when the rocket engine runs out of fuel?
what forces contribute to density
A cat is moving at 18 m/s when it accelerates at 4 m/s2 for 2 seconds. what is his new velocity?
Answer:
26m/s
Explanation:
Acceleration is the change in velocity of a body with respect to time. Mathematically,
Acceleration = change in velocity/time
Acceleration = final velocity (v) - initial velocity (u)/time (t)
Given a = 4m/s², v = ? u = 18m/s, t = 2seconds.
Substituting in the given formula,
4 = v-18/2
8 = v-18
v = 8+18
v = 26m/s
The new velocity of the body is therefore 26m/s
When Babe Ruth hit a homer over the 10
m
-high right-field fence 80
m
from home plate, roughly what was the minimum speed of the ball when it left the bat? Assume the ball was hit 0.90
m
above the ground and its path initially made a 45
∘
angle with the ground
The query involves the application of physics specifically taking into consideration projectile motion. The minimum speed of the ball when it left the bat, assuming a 45° launch angle and no air resistance, is calculated to be approximately 28.36 m/s.
Explanation:This is a question about projectile motion in physics and requires the understanding and application of kinematic equations. Projectile motion assumes air resistance is negligible, and the only force operating on the object is gravity.
The formula to calculate the initial velocity (or speed when the angle is 45°) of the projectile is v = sqrt((g * d) / sin(2θ)), where g is the acceleration due to gravity (approx. 9.8 m/s²), d is the distance, and θ is the launch angle.
So plugging in the values: sqrt((9.8 m/s² * 81 m) / sin(90°)) gives us approximately 28.36 m/s. Therefore, the minimum speed of the ball when it left the bat, assuming a 45° launch angle, is roughly 28.36 m/s.
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A student pushes a box with a total mass of 50kg. What is the net force on the box if it accelerates 1.5m/s^2?
A cannonball is launched from the ground at an angle of 30 degrees above the horizontal and a speed of 30 m/s. Ideally (no air resistance) the ball will land on the ground with a speed of
A. 0 m/s. B. 20 m/s. C. 30 m/s. D. 40 m/s. E. There is not enough information to say.
The answer is not B.
If a block of copper measures 2.00 cm x 4.00 cm x 5.00 cm and weighs 356 grams, what is its density?
The density of the block is 8.9 gm/cm³
What is volume ?
Volume is a three dimensional space occupy by the body of particular shape. Generally expressed in cubic meter.
Here, it is given that length of block (l) = 2 cm
breadth of block (b) = 4 cm
heigth of block (h) = 5 cm
weight of block (m) = 356 gm
the volume of the block is calculated using formula :
[tex]\begin{aligned}V&= lbh\\&=2\cdot4\cdot5\\&=40 \text{ cm}^{3}\end{aligned}[/tex]
Now density of block will be :
[tex]\begin{aligned}\rho&=\frac{m}{V}\\&=\frac{356}{40}\\&=8.9 \:\text{gm}/ \text{cm}^{3}\end{aligned}[/tex]
Therefore, the density of the block is 8.9 gm/cm³
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Superman lived on another planet where the acceleration due to gravity is 23.6 m/s2 . If a woman falls from a building that is 88.3 m tall, how long does he have to save her before she hits the ground?
Acceleration due to gravity = 2.6m/s²
Length of building = d = 88.3m
Time
he needed before she hits the ground = ?
we can find the time by using the
formula;
D = 1/2at²
Now putting the value;
88.3
= (1/2) a t²
88.3 = 1/2 x 23.6 x t²
t² = 88.3 / 11.8
= 7.48
t = 2.735 secondsThe bright, visible surface of the sun is called the
The bright, visible surface of the sun that we see from the earth is called the photosphere, which emits majority of light and has an average temperature of 5500 degrees Celsius.
Explanation:The bright, visible surface of the sun that we see from Earth is known as the photosphere. The photosphere is the layer of the sun where the majority of the light is emitted. It's responsible for the visible light we see, and hence, it appears bright to us. The average temperature of the photosphere is approximately 5500 degrees Celsius. The sunspots, which are darker and cooler areas, can also be observed in this layer due to magnetic activity.
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The __________________ variable is the variable that the scientist changes in an experiment.
If the sun suddenly ceased to shine, how long would it take earth to become dark? you will have to look up the speed of light in a vacuum and the distance from the sun to earth.
If the sun suddenly ceased to shine, then the earth will become dark after 8 min. The speed of light in a vacuum is given as 3* [tex]10^{8}[/tex] m/sec and the distance from the sun to earth is 148.97 million km.
What is speed of light in vacuum?Light moves at about 300,000 kilometers per second in a vacuum, which has a refractive index of 1.0, but it slows to 225,000 kilometers per second in water and 200,000 kilometers per second in glass, both of which have refractive indices of 1.3.
Given that in the question when sun ceased to shine than light on the earth will come after 8 min of ceasing because sunlight takes 8 min to reach on the earth. The speed of light in a vacuum is 186282 miles per second (299792 km/sec.
Light will come after 8 min when sun ceased to shine.
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A duck with a mass of 0.90 kilograms flies at a rate of 12.0 m/s. What is the kinetic energy of the duck?
Answer:
Duck's kinetic energy is 64.8 Joules
Explanation:
It is given that,
Mass of the duck, m = 0.9 kg
Velocity of the duck is, v = 12 m/s
We have to find the velocity of the duck. It is given due to the motion of an object. Mathematically, it is written as :
[tex]KE=\dfrac{1}{2}mv^2[/tex]
[tex]KE=\dfrac{1}{2}\times 0.9\ kg\times (12\ m/s)^2[/tex]
KE = 64.8 Joules
Hence, the kinetic energy of the duck is 64.8 Joules
Like the polar bear, the walrus is a strong swimmer, although it does not have the same endurance. For short periods of time, a walrus can swim at an average speed of 9.7 m/s. How far would a walrus swim at this speed in 3.4 minutes?
base your answers on the following four graphs, which represent the relationship between speed and time for four different objects, A, B, C, and D moving, in a straight line
The required answers are: 1) Object C, 2) Object B, 3) Object C.
Based on the graphs, here are the answers to the given questions:
Object C had a reta rding force acting on it. This is because its speed is decreasing over time, which means it is decelerating.
Object B was not accelerating. This is because its speed is constant over time.
Object C traveled the greatest distance in the 3.0-second time interval. The area under the speed-time curve represents the distance traveled, and Object C's curve has the largest enclosed area.
Area = Triangle + rectangle
A = 1/2 x base x height + length x breadth
A = 1/2 x 3 x (30-20) + 3 x 20
A = 15 + 60
A = 75 = distance in meters.
Complete Question:
Based your answers to questions on the following four graphs, which represent the relationship between speed and time for four different objects, A, B, C, and D moving, in ạ straight line.
1. Which object had a reta rding force acting on it?
2. Which object was not accelerating?
3. Which object traveled the greatest distance in the 3.0-second time interval?
The current through a 12v lamp when it is connected to a 12v battery is 2.0 A. Calculate the resistance of the lamp at this current
The resistance of a lamp connected to a 12v battery that generates a current of 2.0A is calculated using Ohm's law to be 6 ohms.
Explanation:The question asks about the resistance of a lamp connected to a 12v battery that generates a current of 2.0 A.
Using Ohm's law which states that voltage(V) equals current(I) times resistance(R), or V = IR , we can calculate the resistance. In this case, we know the current (I) is 2.0 A and the voltage (V) is 12 V.
We rearrange the formula to find R (resistance) = V/I. Substituting the given values, we have: R = 12v/2.0A = 6 ohms.
Hence, the resistance of the lamp at the current of 2.0 A is 6 ohms.
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