Final answer:
When you open a fridge door, the process is endothermic because the refrigerator absorbs heat from the warm air that enters, which cools the inside.
Explanation:
When you open a fridge door, the process is endothermic. The refrigerator absorbs heat from the surroundings to cool the items inside. During this process, the system (inside of the fridge) gains heat from the warm air that enters when the door is open. By convention, the sign of q (the quantity of heat) for an endothermic process is positive because the system is gaining heat. On the other hand, an exothermic process would be like the inside of a freezer making ice, where heat is removed from the water to freeze it, thus releasing heat to the surroundings.
Understanding the endothermic nature of refrigeration is essential for designing efficient cooling systems, as it allows for the controlled absorption of heat to maintain lower temperatures inside the fridge. The principles of endothermic and exothermic processes guide the engineering of various thermal systems, influencing their energy efficiency and overall performance.
Which is not an assumption about particles in a gas according to the kinetic theory?
The motion of one particle is unaffected by other particles unless the particles collide.
The forces of attraction among particles keep the particles close together.
Under ordinary conditions, forces of attraction between particles can be ignored.
What are the set of equations called that can be used to quantify motion in the case of uniform acceleration?
gravitational laws
kinematic equations
rules for significant figures
Newton's laws of motion
Which of the following is an example of how light does NOT require a medium?
A. Light is unable to pass through a wall.
B. Light can travel through space to reach Earth.
C. Light transmits energy from one place to another.
D. Light can pass through a glass window undisturbed.
There are 206 _____ in the human body that work together to form the _______ system.
The human body contains 206 bones which collectively make up the skeletal system, providing structure, protection, and enabling movement. Bones also play vital roles in the production of blood cells and storing nutrients.
Explanation:There are 206 bones in the human body that work together to form the skeletal system. This system offers protective support for the body's organs, creates blood cells, stores minerals, and enables movement. For instance, the skull shields the brain, the ribs protect the heart and lungs, the spine safeguards the spinal cord, and the pelvis shields the reproductive and digestive organs. The skeletal system and muscular system are the reasons we can move.
Bones also generate our blood cells in the bone marrow, and store some types of minerals such as calcium and phosphate.
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1. Which of these is necessary for a reasonable order-of-magnitude estimate of the speed of a falling object?
a. Round all numbers to the nearest whole number.
b. Have a correct and exact value for the distance of the fall.
c. Use numbers for the time and distance of the fall that are reasonable even if inexact.
d. Assume that any falling object takes about a second to reach the ground
Approximately 80% of the energy used for active transport is devoted to the reabsorption of __________.
Mechanical (sound) waves are unable to travel through a vacuum, such as through space, but radio waves are transmitted to earth from satellites. how is this possible?
a.radio waves are electromagnetic waves.
b.satellites are located within our atmosphere.
c.radio waves are very high energy mechanical waves.
d.radio waves are changed to gamma rays for transmission.
Some enterprising physics students working on a catapult decide to have a water balloon fight in the school hallway. the ceiling is of height 3.6 m, and the balloons are launched at a velocity of 11 m/s. the acceleration of gravity is 9.8 m/s 2 . at what angle must they be launched to just graze the ceiling?
[tex]50^\circ[/tex] angle above the horizontal.
Step by Step Solution :
Given :
Launch speed = 11 m/sec
Height of the ceiling = 3.6 m
[tex]\rm g = 9.8\;m/sec^2[/tex]
Calculation :
Let [tex]\theta[/tex] be the launch angle, measured above the horizontal.
Vertical component of initial speed is
[tex]\rm v = 11sin\theta[/tex]
We know that
[tex]\rm v^2 - u^2=2as[/tex]
[tex]\rm 11^2 sin^2\theta - 2\times9.8\times 3.6 =0[/tex]
[tex]\rm sin\theta = 0.7636[/tex]
[tex]\rm \theta = sin^-^10.7636[/tex]
[tex]\theta = 49.8^\circ \approx 50^\circ[/tex]
[tex]50^\circ[/tex] angle above the horizontal they launched to just graze the ceiling.
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n order to climb a steep hill on a bicycle, a rider shifts to the lowest gear. The lowest gear has the greatest mechanical advantage because it
At the center of each atom lies the atomic ___ which consists of _____ and ______
Final answer:
The atomic nucleus, located at the center of an atom, consists of positively charged protons and neutral neutrons. Electrons orbit this nucleus, and while protons and neutrons give the atom most of its mass, electrons define its size and chemical properties. Thus the sentence is - At the center of each atom lies the atomic nucleus which consists of protons and neutrons.
Explanation:
At the center of each atom lies the atomic nucleus which consists of protons and neutrons.
The nucleus is a positively charged region at the center of the atom. It is composed of protons, which have a positive electric charge, and neutrons, which are neutral. This nucleus is very dense and contains the vast majority (99.97%) of an atom's mass. Surrounding the nucleus is mostly empty space, where negatively charged particles called electrons orbit the nucleus. The structure of an atom is such that the protons and neutrons form the nucleus in the center, while the electrons move around the nucleus in varying energy levels, known as electron shells.
In most atoms, the number of protons and neutrons is the same, giving the atom a balanced, neutral charge overall. The key exception to this is the most common isotope of hydrogen, which consists of only one proton and one electron, with no neutrons in the nucleus. Atomic structure determines the chemical properties of an element, and the arrangement and number of basic particles—protons, neutrons, and electrons—shape these properties.
What property do the following elements have in common? Li, C, and F A) They are poor conductors of electricity. B) Each element participates in covalent bonding. C) They all exist in the same phase at room temperature. D) The valence electrons for each element is located in the same energy level.
Answer: Option (D) is the correct answer.
Explanation:
The given elements Li, C and F are all second period elements. So, when we move from left to right across a period then there occurs increase in number of valence electrons as there occurs increase in total number of electrons.
So, it means more electrons are added to the same energy level.
Thus, we can conclude that a property of valence electrons for each element is located in the same energy level is common in the given elements.
Answer:
the answer is d
Explanation:
i did the usa test prep
A volcano erupted on an island. The entire plant community was destroyed and the island was covered with grey ash. Slowly, lichens and mosses started growing on the island. They helped in the process of soil formation and later other plants started growing too.
Final answer:
Primary succession occurs when new land is formed, and pioneer species like lichens and mosses help break down the rock and create soil.
Explanation:
Primary succession occurs when new land is formed, such as after a volcanic eruption. The pioneer species, like lichens and mosses, help break down the rock and create soil. As the soil develops, other plants can grow and replace the pioneer species. This process eventually leads to an equilibrium state with a diverse set of organisms.
Which of the following is defined as displacement over change in time?
A. Speed
B. Acceleration
C. Velocity
D. Displacement
The first step to using ecology to solve environmental problems is to
a. ban the burning of fossil fuels.
b. close businesses that pollute.
c. use alternative fuels.
d. identify the problem.
Answer: d. identify the problem
Explanation:
Identify the problem is the correct option this is because of the fact that the natural environment may experience disturbance due human intervention like burning of fossil fuels, pollution or due to natural calamity like earthquakes, landslides and volcanic eruptions. To solve these problems detection of problem should be the first step that can lead to mitigation. These problems exerts negative influence over the ecosystem hence are detectable.
What involves extensive in depth studies of an individual?
Why is the wavelength of a moving soccer ball not detectable to the naked eye?
This is mainly because the wavelength of a moving soccer ball is extremely small so it is not detectable to the naked eye. The wavelength of a moving soccer ball is much smaller than what the human eye can pick up, so it cannot be seen.
The wavelength of a moving soccer ball is too small to be detected due to the ball's large mass. This tiny wavelength is immeasurable and has no noticeable effect on the soccer ball's behavior. The de Broglie wavelength is significant only for particles with small mass or high velocity.
The concept of wavelength in matter is explained by the de Broglie wavelength, which is only noticeable for particles with very small mass and/or very high velocity.
For macroscopic objects like a soccer ball, which have a large mass, the wavelength is extremely small. To illustrate, even if a soccer ball were moving at a high speed, its wavelength would still be smaller than the size of an atom, making it impossible to detect with our senses or any known instruments.In summary, while matter waves are a fundamental concept in physics, the wavelengths associated with large objects such as a soccer ball are so minuscule that they have no observable impact on the motion of the ball.what phase are daughter cells in as a result of mitosis
Mitosis results in daughter cells that are in the 'Interphase' of the cell cycle. During this phase, cells prepare for division by duplicating their DNA and growing in size. This phase contains the sub-phases G1, S, and G2 during which cell growth and DNA replication occur.
Explanation:The process of cell division, known as mitosis, results in daughter cells that are in the Interphase. This phase represents the period between cell divisions and is the phase in which cells typically spend the most time. During Interphase, the cell prepares for division by duplicating its DNA and increasing its volume in preparation for cell division. The nucleus is visible and contains a nucleolus. The Interphase is categorized into three sub-phases: G1 (gap 1) phase, S (synthesis) phase, and G2 (gap 2) phase. Cell growth occurs during the G1 and G2 phases, while DNA replication occurs during the S phase.
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A cartoon shows two friends watching an unoccupied car in free fall after it has rolled off a cliff. one friend says to the other "It goes from zero to sixty miles per hour in about three seconds." is this statement correct?
The statement is not correct because the velocity of the car in a free fall after 3 seconds is 29.4 m/s while the assumed velocity of the friend is 26.82 m/s.
The given information;
assumed initial velocity of the car, u = o assumed final velocity of the car, v = 60 miles per hourtime of motion, t = 3 secondsThe velocity of an object under the influence of gravity;
v = u + gt
where;
g is acceleration due to gravity = 9.8 m/s²
Convert the given final velocity in mph to m/s;
[tex]v = 60 \ \frac{miles}{hour} \times \frac{1609.34 \ m}{1 \ mile} \times \frac{1 \ hour}{3600 \ s} = 26.82 \ m/s[/tex]
Determine if the assumed final velocity will be equal to actual velocity in 3 seconds after the motion.
v = 0 + (3 x 9.8)
v = 29.4 m/s
Thus, the statement is not correct because the velocity of the car in a free fall after 3 seconds is 29.4 m/s while the assumed velocity of the friend is 26.82 m/s.
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1) Which of the following alternative energy sources is NOT inexhaustible?
tidal energy
solar energy
geothermal energy
wind energy
2) Which of the following is a problem associated with the increased use of nuclear energy?
cost of building sage nuclear facilities
major hazards involved in nuclear waste disposal
concern over the possibility of a serious nuclear accident
all of the above
3) One problem with wind energy as a major source of electricity is ________.
it is nonrenewable
it causes major air polution
it does not work at night
the expense of large tracts of the land in populated areas
Your most reliable answer my friend would be 1. Wind 2. All of the above 3. The expense of large tracts of land in populated areas
When a 85 kg man sits on the stool, by what percent does the length of the legs decrease? assume, for simplicity, that the stool's legs are vertical and that each bears the same load?
Final answer:
To determine the percent decrease in the stool's leg length under a man's weight, additional information such as the original leg length and material properties are required. Using Hooke's law or relevant formulas, we could then calculate the strain and convert it to a percentage.
Explanation:
To calculate by what percent the length of the legs of a stool decrease when an 85 kg man sits on it, we need certain information that is not provided in this scenario, such as the original length and material properties of the stool's legs (e.g., the Young's modulus if we assume the legs are cylindrical rods), as well as the assumption that each leg bears the same load.
Without this additional information, we cannot calculate the exact percentage change in length. If this information were available, we would use Hooke's law, which is commonly used to determine the deformation caused by applying a force on a spring. We would also consider the modulus of elasticity for materials that are not springs. The change in length (ΔL) divided by the original length (L0) gives the strain, which can be multiplied by 100 to find the percentage deformation.
The length of the stool's legs decreases by approximately 0.00083% when a 85 kg man sits on it.
Calculating Deformation of Stool Legs
To determine the percent decrease in the length of the legs of a stool when a 85 kg man sits on it, we can use the formula for linear deformation:
[tex]\Delta L = (F \times L) / (A \times Y)[/tex]
Where:
[tex]\Delta L[/tex] is the change in length.F is the force applied.L is the original length of the legs.A is the cross-sectional area of the legs.Y is the Young's modulus of the material.Assuming each of the stool’s four legs equally shares the weight of the man, the force per leg due to the man’s weight is:
[tex]F = (85 kg \times 9.81 m/s^2) / 4 = 208.42 N[/tex]
Let’s assume the original length (L) of the legs is 0.5 meters and the radius of the legs is 0.02 meters. The cross-sectional area (A) can be calculated using the formula for the area of a circle: [tex]A = \pi \times r^2[/tex]
Thus, the cross-sectional area is:
[tex]A = \pi \times (0.02 m)^2 = 1.2566 \times 10^{-3} m^2[/tex]
Assuming the legs are made of a material with Young's modulus (Y) of [tex]2 \times 10^{10} N/m^2[/tex], the change in length (ΔL) is:
[tex]\Delta L = (208.42 N \times 0.5 m) / (1.2566 \times 10^{-3} m^2 \times 2 \times 10^{10} N/m^2) = 4.15 \times 10^{-6} meters[/tex]
To find the percent decrease in length:
[tex]\text{Percent Decrease} = (\Delta L / L) \times 100 = (4.15 \times 10^{-6} m / 0.5 m) \times 100 = 0.00083\%[/tex]
Therefore, the length of the stool's legs decreases by approximately 0.00083% when the 85 kg man sits on it.
Uranus has an orbital period of 84.07 years. In two or more complete sentences, explain how to calculate the average distance from Uranus to the sun and then calculate it.
The formula is p^2=a^3
Answer:
Average distance from Uranus to the sun, a = 2.88 billion km
Explanation:
It is given that,
Orbital period of Uranus, T = 84.07 years = 2.65 × 10⁹ s
We have to find the average distance from Uranus to the sun. It can be calculated using Kepler's third law as :
[tex]T^2\propto a^3[/tex]
or [tex]T^2=\dfrac{4\pi^2}{GM}a^3[/tex]
Where
T is orbital period
a is the average distance from Uranus to the sun
G is universal gravitational constant
M is mass of sun, [tex]m=1.98\times 10^{30}\ kg[/tex]
[tex]a^3=\dfrac{T^2GM}{4\pi^2}[/tex]
[tex]a^3=\dfrac{(2.65\times 10^9)^2\times 6.67\times 10^{-11}\times 1.98\times 10^{30}}{4\pi^2}[/tex]
[tex]a^3=2.34\times 10^{37}\ m[/tex]
[tex]a=2.86\times 10^{12}\ m[/tex]
a = 2.88 billion km
Hence, this is the required solution.
Which chemical reaction involving water is a decomposition reaction (breaking up) and which is a synthesis (building up) reaction?
A decomposition reaction would be the electrolysis.
Usually it is separated in two equations, one for oxidation and another for reduction, which are called half reactions:2 H+ + 2e− → H2
2 H2O → O2 + 4 H+ + 4e−
Then you should add them up. In order for the equation to be balanced, the first equation has to be added twice:
2 H+ + 2e− + 2 H+ + 2e−+2 H2O → H2+ H2 + O2 + 4 H+ + 4e−
4 H+ + 4e− +2 H2O → 2H2 + O2 + 4 H+ + 4e−
Then you should cancel the substances which are both in reactives and in products, and also the electrons:
2 H2O → 2H2 + O2
And there you have the overall equation for electrolysis.
Electrolysis does not happen naturally – you have to provide electric energy for it to happen.
A synthesis reaction would be the opposite reaction, which would be called: electrosyntesis.
2H2 + O2 → 2 H2O
You throw a 20-n rock vertically into the air from ground level. you observe that when it is a height 15.4 m above the ground, it is traveling at a speed of 24.2 m/s upward.
I believe there are two things which we asked to find here:
1. its speed just as it left the ground
2. find its maximum height
Solutions:
1. We use the formula:
ΔKE = - ΔPE
where KE is kinetic energy = ½ mv^2, and PE is potential energy = m g h, Δ = change
Therefore:
½ m (v2^2 – v1^2) = m g (h1 – h2)
at initial point, point 1: h1 = 0, v1 = ?
at final point, point 2: h2 = 15.4 m, v2 = 24.2 m/s
½ (24.2^2 – v1^2) = 9.8 (0 – 15.4)
585.64 – v1^2 = -301.84
-v1^2 = 887.48
v1 = 29.8 m/s
So the rock was travelling at 29.8 m/s as it left the ground.
2. The maximum height (hmax) reached is calculated using the formula:
v1^2 = 2 g hmax
Rewriting in terms of hmax:
hmax = v1^2 / 2 g
hmax = (29.8)^2 / (2 * 9.8)
hmax = 45.3 m
Therefore the rock reached a maximum height of 45.3 meters.
This high school physics question discusses the principles of kinematics and energy conservation. Given the speed and height of a rock thrown vertically upwards, it asks to determine the initial speed of the rock. We calculate this using the given values and the formula for kinetic energy & gravitational potential energy conservation, getting the initial velocity as approximately 16.88 m/s.
Explanation:The subject of this question pertains to physics, specifically the application of the principles of kinematics and energy conservation in studying projectile motion. Neglecting air resistance, the speed of a projectile (like a rock) thrown vertically upwards at a certain height from the ground can be calculated using energy considerations. From the given, the rock is starting from ground level with a certain velocity upwards and it is observed that at a height of 15.4 m, its speed is 24.2 m/s. Let's denote the initial speed when the rock was thrown as v0.
Using the equation v = √(2gh + v0²), where g is the acceleration due to gravity (9.8 m/s²) and h is the height (15.4 m), we can find the initial velocity of the rock. Plugging in the known values, we get v0 as √[(24.2 m/s)² - 2*(9.8 m/s²)×15.4 m] = √(585.64-301.6) m/s = √284.04 m/s = 16.88 m/s.
This calculation tells us the initial speed required to achieve the observed height and speed. This information can be crucial in physical scenarios involving projectiles.
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A boy kicks a football from ground level with an initial velocity of 20 m/s at an angle of 30° above the horizontal. what is the horizontal distance to the point where the football hits the ground if we neglect air resistance?
a.60 m
b.18 m
c.30
The question involves the Physics concept of projectile motion. By substituting g the given values into the relevant equations for horizontal distance and time, we conclude that the football will travel 60m before hitting the ground.The correct answer is option A.
Explanation:This question is about a fundamental concept in Physics: projectile motion. To find the horizontal distance a projectile travels, we can use the following formula.
Here, the horizontal distance (d) is given by the equation d = (vi × t × cos(θ)), where vi is the initial velocity (20m/s), t is the time the football is in the air, and cos(θ) is the cosine of the angle of projection (30°).
The time the ball is in the air can be found by using the equation t = 2×vi×sin(θ) / g, where g is the gravity constant (9.8 m/s2).
Substituting the known values into these equations, we conclude that the football will travel 60m before it hits the ground, thus the answer is a.60 m.
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If a star is less than 10 parsecs from us, what can we say about how its apparent and absolute magnitudes compare? hints they will be the same number. more information is needed to make a judgment. absolute magnitude will be the larger number. apparent magnitude will be the larger numbe
After the same car leaves the platform, gravity causes it to accelerate downward at a rate of 9.8 m/s2. What is the gravitational force on the car?
Two electric motors drive two elevators of equal mass in a three-story building 10 meters tall. each elevator has a mass of 1,000 kg. the second elevator takes 10 seconds to do this work. calculate the power output of the second motor.
Final answer:
The power output of the second motor that drives the elevator is 9,810 watts or 9.81 kilowatts, calculated by dividing the work done (which is the change in gravitational potential energy) by the time taken.
Explanation:
To calculate the power output of the second motor that drives the elevator, we need to use the formula for power: P = W/t, where P is power, W is work done, and t is time taken.
Since the work done by the motor in lifting the elevator is equal to the change in gravitational potential energy, W = mgh, where m is the mass of the elevator, g is acceleration due to gravity (9.81 m/s²), and h is the height the elevator is lifted. For the second elevator, the mass m is 1,000 kg, height h is 10 meters, and the time taken t is 10 seconds.
First, calculate the work done:
W = mgh = (1,000 kg)(9.81 m/s²)(10 m) = 98,100 J (joules)
Now, calculate the power:
P = W/t = 98,100 J / 10 s = 9,810 W
Therefore, the power output of the second motor is 9,810 watts or 9.81 kilowatts (kW).
Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr?
Answer:answer is twice as much
Explanation:
The density of gold is 19.3 g/cm3. A piece of gold displaces 2 mL of water. The specific gravity of gold is:
A.19.3
B.38.6
C.9.6
D.0.10
Answer:
A) 19.3
Explanation:
As we know that specific gravity is defined as the ratio of weight of the object and weight of the water displaced by the object
so it is given by
[tex]Specific \gravity = \frac{weight \: of \: object}{weight \: of \: water\: displaced}[/tex]
now we have
weight of the object = (density)(volume)g
weight of object = [tex](19.3 g/cm^3)(2 mL)g[/tex]
now weight of the liquid displaced is given by
weight of water displaced = [tex](1 g/cm^3)(2 mL)g[/tex]
now we have
specific gravity = [tex]\frac{(19.3)(2mL)g}{(1)(2 mL)g}[/tex]
specific gravity = 19.3
Can the momentum of an object change