Work & Energy Test
A horse does 910 J of work in 380 seconds while pulling a wagon. What is the power output of the horse? Round your answer to two significant figures. The power output of the horse is _______ W
2.4
Tracy makes a list of energy transformations that occur as an engine runs to power a car. 1. Chemical energy transforms into thermal energy. 2. Thermal energy transforms into electrical energy. 3. Chemical energy transforms into gravitational potential energy. 4. Thermal energy transforms into kinetic energy. Which transformation should Tracy remove from the list? 1 2 3 4
3
A blender takes in 180 J of electrical energy. Of the 180 J, 90 J are transformed into kinetic energy, 60 J are transformed into thermal energy, and the rest is transformed into sound. What is the sound energy generated by the blender? 30 J 90 J 150 J 330 J
30 J
Why is it important to know the direction of the force applied to a moving object and the direction in which the object is moving when determining the work done on the object?
When there is an angle between the two directions, the cosine of the angle must be considered.
Which best summarizes a concept related to the work-energy theorem? When work is positive, the environment does work on an object. When work is negative, the environment does work on an object. When work is positive, the kinetic energy in a systemremains constant. When work is negative, the kinetic energy in a system remains constant.
When work is positive, the environment does work on an object.
They have been successful, but they are very expensive to operate.
Which best describes fusion nuclear reactors?
gravitational lensing
Which concept was supported by taking measurements of the same stars at night and then again during solar eclipses?
The diagram shows an inclined plane. (Length is 120 in, Height is 30 in) What is the mechanical advantage of the inclined plane?
4
A toy plane has a mass of 2.5 kg and is 18 m above the ground. It is moving at 4.5 m/s. How much mechanical energy does the toy plane have? 416 J 441 J 466 J 491 J
466 J
Carlos uses a rope to pull his car 30 m to a parking lot because it ran out of gas. If Carlos exerts 2,000 N of force to pull the rope, and the rope is at an angle of 15° to the road, how much work did he do? Round your answer to two significant figures.
5.8 × 104 J
What must be true of an object that has gravitational potential energy?
It is above a reference point.
According to the work-energy theorem, the amount of work done can be determined using which formula?
W = /\ KE = 1/2m (v2f - v2i)
According to the work-energy theorem, the amount of work done can be determined using which formula? W = KE = 2m(v2i-v2f) W = KE = 1/2m(v2i-v2f) W = KE = 2m(v2f-v2i) W = KE = 1/2m(v2f-v2i)
W = KE = 1/2m(v2f-v2i)
Examine the scenarios. Scenario W: A force of 75 N moves a box 15 m. Scenario X: A force of 100 N moves a box 12 m. Scenario Y: A force of 50 N moves a box 20 m. Scenario Z: A force of 25 N moves a box 45 m. In which scenarios is the same amount of work done on the box? W and X W and Z X and Y Y and Z
W and Z
Which change would increase the mechanical advantage of dentures, which are artificial teeth?
an increase in the length of the sloped side of the teeth and a constant width of the teeth
three conditions that must be met for work to be done
an object must be displaced,a force must cause the displacement,the force and the displacement must be met on the same axis
How is power calculated? multiply force and displacement divide force by displacement multiply work and time divide work by time
divide work by time
What is the best description of the energy stored in a stretched or compressed object?
elastic potential
What is the best description of the energy stored in a stretched or compressed object? gravitational potential potential energy elastic potential spring constant
elastic potential
kinetic energy
energy a moving object has because of its motion; depends on the mass and speed of the object.
law of conservation of energy
energy can change form but it is never created or destroyed.The total amount of energy in the universe is constant
Energy can be changed from one form to another. Which terms can be used to describe these changes? Check all that apply. energy conversion energy conservation energy correlation energy transformation energy transference
energy conversion energy transformation
gravitational potential energy
energy stored by objects due to their position above Earth's surface; depends on the distance above Earth's surface and the object's mass.
chemical potential energy
energy stored in chemical bonds.
elastic potential energy
energy stored when an object is compressed or stretched.
The work-energy theorem states that the work done on an object is equal to a change in which quantity? kinetic energy displacement potential energy mass
kinetic energy
what are the big 4 conservation laws?
mass,energy,momentum,electrical charge(these quantities are always conserved in all physical and chemical reactions)
Energy transformations that involve one transformation from one type of energy to another are called transformations.
single
The measure of a spring's resistance to being compressed or stretched is the ___________________________
spring constant
Which factor affects elastic potential energy but not gravitational potential energy? spring constant acceleration due to gravity distance from a given position amount of matter in the object
spring constant
law of conservation of energy
states that energy can never be created or destroyed.
potential energy
stored energy an object has due to its position.
potential energy
stored energy. Energy that an object has due to its position or shape
mechanical energy
sum of the potential energy and kinetic energy in a system.
energy
the ability to do work and cause a change to occur.
kinetic energy
the energy of a moving object,depends on mass and speed
power
the rate at which work is done and the rate at which energy transformed(unit is Watt)
mechanical energy
the sum of an objects kinetic energy plus its potential energies
Which formula can be used to find velocity if kinetic energy and mass are known? v = (square root)1/2(KE)(m) v = (square root)2m/KE v = (square root)KE(m) v = (square root)2KE/m
v = (square root)2KE/m
the angle between the force vector and the displacement vector
what determines the sign of work?
it transforms it to thermal energy
what does friction do to mechanical energy?
height compared to a zero level
what does gravitational potential energy depend on?
kinetic energy changes
what happens to the kinetic energy when work is done on the object?
conserved quantities
when a quantity is conserved it is constant
when a force causes the displacement of the object
when is work done an object?
lifting an object
work is always done when...?
A ball has 116.62 J of gravitational potential energy at a height of 85 m. What is the mass of the ball?
0.14 kg
A ball has 116.62 J of gravitational potential energy at a height of 85 m. What is the mass of the ball? 0.14 kg 0.37 kg 11.9 kg 21.82 kg
0.14 kg
A bird flies off of a cliff, dropping a feather and knocking rocks off the cliff. The rocks reach the ground much faster than the feather. Which energy transformations occur in this case? Check all that apply.
- Some of the potential energy of the feather is converted into kinetic energy. - All of the feather's potential energy is converted into thermal energy due to the friction of air resistance. - Some of the feather's potential energy is converted into thermal energy due to the friction of air resistance.
A moving company collects data about couches they move and displays the data in a table. The force along the ramp, the angle of the ramp, and the height the couch is raised to are shown. Which statements correctly compare the work done to move the couches? Check all that apply.
- The work for couch 2 is less than the work for couch 3. - The work for couch 3 is greater than the work for couch 1. - The work for couch 2 is greater than the work for couch 1.
A 60.0 kg object is moving east at 8.00 m/s, and then slows down to 4.00 m/s. How much work was done?
-1,440 J
Which statements describe a situation in which work is being done? Check all that apply
-A box is carried up a flight of stairs by a mover. -Wind blows a pool chair across the yard. -A weightlifter lifts a barbell off the ground
Which situations describe unbalanced forces? Check all that apply.
-a pitcher throwing a baseball -a car accelerating downhill -a toy rocket being launched into the air
The energy transfer diagram represents the energy of a person diving into a pool. (Output of 7,000 from 8,000) How much thermal energy is generated?
1,000 J
If 3,600 J of work is done in 3.0 s, what is the power?
1,200 W
Every spring has an equilibrium position. Which statements describe a spring at its equilibrium position? Check all that apply.
1,3,5
About how much work does Luke do on the sled?
1,500 J
Luke pulls a sled using a force of 65 N for a distance of 25 m across level ground. The rope Luke pulls forms an angle of 25° with the ground. About how much work does Luke do on the sled?
1,500 J
If 120 N of force is applied to a crate to move it 15 m, how much work is done?
1,800 J
A force of 100 N is applied to a crate at an angle of 60° to the horizontal surface. The force causes the crate to move 2 m across the floor. How much work is done on the crate?
100 J
A compressed spring has 16.2 J of elastic potential energy when it is compressed 0.30 m. What is the spring constant of the spring?
108 N/m
To the nearest whole number, the pumpkin will rise m.
15
Pravat exerts a force of 30 N to lift a bag of groceries 0.5 m. How much work did Pravat do on the bag?
15 J
A 2.50 × 105 W motor is used for 26.4 s to pull a boat straight toward shore. How far does the boat move toward shore if a force of 4.20 × 104 N is applied by the motor? 157 m 1,590 m 1.11 × 106 m 6.60 × 106 m
157 m
A spring that has a spring constant of 1400 N/m is stretched to a length of 2.5 m. If the normal length of the spring is 1.0 m, how much elastic potential energy is stored in the spring?
1575 J
Natalia lifts a bag of groceries 0.50 m by exerting a force of 36 N. How much work did she do on the bag? 0 J 18 J 36 J 72 J
18 J
A 20.0 kg object is at rest, and then speeds up to 16.0 m/s. How much work was done on this system?
2,560 J
An eagle that has a mass of 4.5 kg is spotted 5 m above a lake. It flies up to its nest in a tree at a height of 25 m. How much gravitational potential energy did the eagle gain?
221 J
What is the kinetic energy of a 620.0 kg roller coaster moving with a velocity of 9.00 m/s?
25,100 J
What is the kinetic energy of a 620.0 kg roller coaster moving with a velocity of 9.00 m/s? 2,790 J 5,580 J 25,100 J 50,200 J
25,100 J
A bird has a kinetic energy of 3 J and a potential energy of 25 J. What is the mechanical energy of the bird? 3 J, because mechanical energy is the same as kinetic energy 22 J, because mechanical energy is the difference of the potential energy and kinetic energy 25 J, because mechanical energy is the same as potential energy 28 J, because mechanical energy is the sum of the potential energy and kinetic energy
28 J, because mechanical energy is the sum of the potential energy and kinetic energy
A 5,400 W motor is used to do work. If the motor is used for 640 s, about how much work could it do? 8.4 J 4,800 J 6,000 J 3,500,000 J
3,500,000 J
A forklift raises a 1,020 N crate 3.50 m up to a shelf. How much work is done by the forklift on the crate? The forklift does ______________ J of work on the crate
3,570
If a car used 260,000 W of power to complete a race in 15 s, how much work did the car do?
3,900,000 J
A baseball has a mass of 0.145 kg and is 12 m above the ground. If it has a mechanical energy of 105.8 J, how fast is it moving? 17 m/s 35 m/s 89 m/s 130 m/s
35 m/s
A compressed spring has 16.2 J of elastic potential energy when it is compressed 0.30 m. What is the spring constant of the spring?
360 N/m
A compressed spring has 16.2 J of elastic potential energy when it is compressed 0.30 m. What is the spring constant of the spring? 90 N/m 108 N/m 180 N/m 360 N/m
360 N/m
The mass of an object with 500 J of kinetic energy moving with a velocity of 5 m/s is kg. (Report the answer to one significant figure.)
40
An 85 kg construction worker has 37,485 J of gravitational potential energy. To the nearest whole number, the worker is _____ m above the ground.
45
A diver who has a mass of 68 kg climbs to a diving platform that is 7.5 m above the surface of a pool. How much gravitational potential energy does the diver have in relation to the pool's surface?
4998 J
A bulldozer does 4,500 J of work to push a mound of soil to the top of a ramp that is 15 m high. The ramp is at an angle of 35° to the ground. How much force did the bulldozer apply to the mound of soil? Round your answer to two significant figures.
520 N
A ball that has a mechanical energy of 65 J has 12 J of kinetic energy. The ball has ⇒ of potential energy.
53 J
If a 4.5 kg object is dropped from a height of 6.0 m, what will be its velocity when it is halfway toward the ground? (Use g = 9.80 m/s2, and ignore air resistance.)
7.7 m/s
The potential energy of a 25 kg bicycle resting at the top of a 3 m high hill is?
75 J
A crane does 9,500 J of work to lift a crate straight up using a force of 125 N. How high does the crane lift the crate? 0.013 m 76 m 9,400 m 1,200,000 m
76 m
To do work, this truck uses energy stored in chemical fuel and an electrical battery. (Output of 400, 250, 150) How much total energy does this truck put out?
800 J
The kinetic energy of an object with a mass of 6.8 kg and a velocity of 5.0 m/s is J. (Report the answer to two significant figures.)
85
An eagle that has a mass of 4.5 kg is spotted 5 m above a lake. It flies up to its nest in a tree at a height of 25 m. How much gravitational potential energy did the eagle gain?
882 J
An eagle that has a mass of 4.5 kg is spotted 5 m above a lake. It flies up to its nest in a tree at a height of 25 m. How much gravitational potential energy did the eagle gain? 221 J 882 J 1103 J 1323 J
882 J
Wapi collected data about four machines and listed it in this table. Which machine has the greatest output force?
A
-1,440 J
A 60.0 kg object is moving east at 8.00 m/s, and then slows down to 4.00 m/s. How much work was done?
3.1 m/s
A bicycle tire has a radius of 0.23 m. The tire spins at a constant speed with a centripetal acceleration of 42 m/s2. What is the tangential speed of the tire?
The west component is a negative number, and the north component is a positive number.
A boat travels in a straight path that is 25° west of north. Which describes the values of the west and north components of the boat's displacement?
In which scenario is an animal doing work? Check all that apply. A cat lifts up her kitten by its neck. A dog rubs his back against a large tree. A bird carries a worm to its nest. A goat butts its head against the barn wall. A horse pulls a wagon along a road.
A cat lifts up her kitten by its neck. A bird carries a worm to its nest. A horse pulls a wagon along a road.
0.70 m
A cyclist rides at a constant speed of 4.5 m/s around a curve. If the centripetal acceleration is 29 m/s2, what is the radius of the curve?
In which scenario is elastic potential energy present? A bird sits in its nest in a tree. A snake slithers through a leaf pile. A dog sniffs at the base of a tree. A fly stretches a spider web.
A fly stretches a spider web.
Which is the best example of the law of conservation of energy?
A rolling skateboard slows down because some of its kinetic energy changes to heat
In which scenario is the least amount of work done on a crate? A force of 120 N moves it 25 m. A force of 115 N moves it 26 m. A force of 130 N moves it 22 m. A force of 125 N moves it 27 m.
A force of 130 N moves it 22 m.
Which statement best describes why a machine is useful?
A machine can decrease either the input force or the input distance needed to do a given amount of work.
The work for couch 2 is less than the work for couch 3. The work for couch 3 is greater than the work for couch 1. The work for couch 2 is greater than the work for couch 1.
A moving company collects data about couches they move and displays the data in a table. The force along the ramp, the angle of the ramp, and the height the couch is raised to are shown. Which statements correctly compare the work done to move the couches? Check all that apply.
3
A person riding north on a bicycle speeds up from 0 m/s to 9 m/s in 3 seconds. The acceleration of the bicycle is
1575 J
A spring that has a spring constant of 1400 N/m is stretched to a length of 2.5 m. If the normal length of the spring is 1.0 m, how much elastic potential energy is stored in the spring?
In which scenario is gravitational potential energy present?
A squirrel runs up the trunk of a tree.
15
A vertical spring with a spring constant value of 4500 N/m is compressed 60 cm. A 5.5 kg pumpkin is placed on the end of the spring, and the spring is released. To the nearest whole number, the pumpkin will rise ________
A 60.0 kg runner is moving at 6.00 m/s and speeds up to 9.00 m/s. The runner's change in kinetic energy is 1,350 J. How much work was done?
A. -2,430 J wrong B. -1,350 J C. 1,350 J wrong D. 2,430 J
Four vehicles are traveling on the same road. Which vehicle most likely has the greatest kinetic energy?
A. a compact car traveling at a velocity of 10 m/s B. a pickup truck traveling at a velocity of 25 m/s wrong C. a minivan traveling at a velocity of 10 m/s wrong D. a motorcycle traveling at a velocity of 25 m/s
45
An 85 kg construction worker has 37,485 J of gravitational potential energy. To the nearest whole number, the worker is _______ m above the ground.
Irving, a cat, has a favorite toy that is made up of a squeaky ball at the end of a string. The toy makes up a closed system. Irving's owner dangles the toy so that the ball swings down and then swings back up again. Ignoring any friction, how are kinetic and potential energy related to each other as the ball swings back and forth?
As the ball moves upward, kinetic energy decreases and potential energy increases.
Which energy transformations occur when a candle burns? Thermal energy transforms into mechanical energy and radiant energy. Chemical energy transforms into thermal energy and electrical energy. Thermal energy transforms into radiant energy and chemical energy. Chemical energy transforms into thermal energy and radiant energy.
Chemical energy transforms into thermal energy and radiant energy.
Which formula can be used to find velocity if kinetic energy and mass are known?
D. v = 2KE/m
Kinetic energy and mass are _________________ proportional.
Directly
Earth and all of the air in the atmosphere around it make up an incredibly complex system. Energy is constantly changing forms in many different ways. How would scientists most likely describe the system of the Earth in regard to energy?
Earth is an open system because heat energy from the Sun enters through the atmosphere.
Kristina demonstrates a toy for her younger brother. The steps to operate the toy are listed below. Step 1. Push the toy down. Step 2. A spring compresses. Step 3. Release the toy. Step 4. The toy jumps into the air. Which best describes Step 4?
Elastic potential energy changes to gravitational potential energy.
Which statement best describes what energy transfer diagrams show? Energy can change form, but the total amount of energy stays the same. Every energy transformation results in a reduction of energy. Energy transformations result in fewer types of energy. Each type of energy can change into one other type of energy.
Energy can change form, but the total amount of energy stays the same.
X
Four landing sites are proposed for a lander. Data about the sites are listed in the table. At which landing site would the lander have the greatest amount of gravitational potential energy?
What energy transformation occurs when a skydiver first jumps from a plane? Gravitational potential energy transforms into kinetic energy. Gravitational potential energy transforms into thermal energy. Kinetic energy transforms into gravitational potential energy. Thermal energy transforms into gravitational potential energy.
Gravitational potential energy transforms into kinetic energy.
Which energy transformation occurs after a skydiver reaches terminal velocity?
Gravitational potential energy transforms into thermal energy.
Describe the calculation for speed as "dividing distance by time."
Hannah made a chart to describe speed and velocity. Which best describes how to correct Hannah's error
Trevor is pulling his younger brother in a wagon. He pulls the wagon 50 m to the corner with a force that is parallel with the ground. He then turns the wagon around and pulls it 50 m back to the starting point with the same force at an angle of 30° with respect to the ground. How does the amount of work Trevor performs going to the corner compare with the amount of work he performs coming back? They are the same because he uses the same amount of force. They are the same because he travels the same distance. He does less work coming back because the force moving the wagon is only 50cos30°. He does more work coming back because the force moving the wagon is only 50cos60°.
He does less work coming back because the force moving the wagon is only 50cos30°.
There is uncertainty in each measurement, as indicated by significant figures.
How does uncertainty relate to measurements and calculations made during an investigation?
theory.
In 1859, Charles Darwin published the first edition of On the Origin of Species, which explained his observations of various groups of animals that showed great similarities but minor differences. Darwin concluded that if a population of one species separates into two different populations that live in separate locations, then over the course of many generations the different populations can develop into different species. This idea predicted many future biological findings and became the basis of modern biology. Darwin's explanation for why different species exist is best described as a(n)
Lenny wrote the steps he used to find the mass of an object with 400 J of energy moving at a velocity of 8 m/s. 1. Find the square of 8 m/s, which is 64 m2/s2. 2. Divide kinetic energy, 400 J, by 64 m2/s2, which is 6.25 J per m2/s2. 3. Divide 6.25 J per m2/s2 by 2 to get a mass of 3.125 kg. Which best describes Lenny's error?
In Step 3, he should have multiplied 6.25 J per m2/s2 by 2 instead of dividing it by 2.
Lenny wrote the steps he used to find the mass of an object with 400 J of energy moving at a velocity of 8 m/s. 1. Find the square of 8 m/s, which is 64 m2/s2. 2. Divide kinetic energy, 400 J, by 64 m2/s2, which is 6.25 J per m2/s2. 3. Divide 6.25 J per m2/s2 by 2 to get a mass of 3.125 kg. Which best describes Lenny's error? In Step 1, he should have found the square root of 400 J instead of squaring 8 m/s. In Step 1, he should have multiplied 8 m/s by 2 instead of squaring it. In Step 2, he should have divided 64 m2/s2 by 400 J instead of dividing 400 J by 64 m2/s2. In Step 3, he should have multiplied 6.25 J per m2/s2 by 2 instead of dividing it by 2.
In Step 3, he should have multiplied 6.25 J per m2/s2 by 2 instead of dividing it by 2.
MV2/R
In the equation for centripetal force, which expression represents the centripetal acceleration of the object?
What is the formula for calculating kinetic energy?
KE = ½mv²
Which equation shows the correct relationship between mechanical energy, kinetic energy, and potential energy? ME = KE + PE ME + KE = PE ME = KE - PE ME + PE = KE
ME = KE + PE
If all else is constant, which would cause the greatest increase in kinetic energy of a moving object? Mass and velocity are each reduced by one-half. Mass is reduced by one-half, and velocity is doubled. Mass is doubled, and velocity is reduced by one-half. Mass and velocity are each doubled.
Mass and velocity are each doubled.
No change in mass number occurs in beta minus decay.
Mimi makes a table about the two types of beta decay
Kinetic energy is the energy an object has due to its
Motion
Which best describes how energy changes form in a car's engine? A single transformation occurs because the chemical energy of the fuel is changed to the mechanical energy of the car. A single transformation occurs because the mechanical energy of the car originates from one spark. Multiple transformations occur because the chemical energy of the fuel is changed to several forms of energy. Multiple transformations occur because the chemical energy of the fuel must be replenished to keep the car running.
Multiple transformations occur because the chemical energy of the fuel is changed to several forms of energy.
A 20.0 kg object is at rest, and then speeds up to 16.0 m/s. How much work was done on this system? 320 J 2,560 J 2,880 J 5,120 J
NOT 320 J
A diver who has a mass of 68 kg climbs to a diving platform that is 7.5 m above the surface of a pool. How much gravitational potential energy does the diver have in relation to the pool's surface? 510 J 1912 J 3825 J 4998 J
NOT 3825 J
Kristina demonstrates a toy for her younger brother. The steps to operate the toy are listed below. Step 1. Push the toy down. Step 2. A spring compresses. Step 3. Release the toy. Step 4. The toy jumps into the air. Which best describes Step 4? Elastic potential energy changes to gravitational potential energy. Gravitational potential energy changes to elastic potential energy. Kristina does work to increase the gravitational potential energy. Kristina does work to increase the elastic potential energy.
NOT Kristina does work to increase the gravitational potential energy. NOT Gravitational potential energy changes to elastic potential energy.
Brandi poses as Lady Justice for a skit in her government class. She holds a set of scales above her head with her right hand and a sword by her side in her left hand. She holds the pose for 10 minutes. At the end of the skit, she mentions to her friend that it was a lot of work to pose and that her arms were really tired. Which best summarizes Brandi's statement about doing work while posing? She did no work because she did not exert any forces on objects. She did more work using her right hand than her left because her right hand was higher. She did no work because she did not move the scales or sword while she posed. She did work the entire time she posed because she was tired at the end.
NOT She did work the entire time she posed because she was tired at the end. NOT She did more work using her right hand than her left because her right hand was higher.
Which statement about work and power correctly describes an automobile race? The cars do different amounts of work depending on how fast they finish. The car that finishes last has the lowest power. The car with the greatest power travels the greatest distance. The cars do different amounts of work depending on their power.
NOT The cars do different amounts of work depending on their power.
How does the work needed to lift an object and the gravitational potential energy of the object compare?
NOT The comparison depends on the height.
Lamar writes several equations trying to better understand potential energy. What conclusion is best supported by Lamar's work? The elastic potential energy is the same for any distance from a reference point. The gravitational potential energy equals the work needed to lift the object. The gravitational potential energy is the same for any distance from a reference point. The elastic potential energy equals the work needed to stretch the object.
NOT The elastic potential energy is the same for any distance from a reference point.
Which factor affects elastic potential energy but not gravitational potential energy?
NOT amount of matter in the object NOT distance PRETTY SURE IT IS VELOCITY
Which factor affects gravitational potential energy but not elastic potential energy? spring constant velocity distance mass
NOT distance
Doubling which quantity would cause the largest increase in a spring's elastic potential energy?
NOT gravitational acceleration
Doubling which quantity would cause the largest increase in a spring's elastic potential energy? displacement spring constant mass gravitational acceleration
NOT gravitational acceleration
Which statement best compares potential and kinetic energy?
Only kinetic energy increases when the velocity of an object increases.
The rate at which work is done is
Power
joule
SI unit of energy.
The image shows a pendulum that is released from rest at point A. Shari tells her friend that no energy transformation occurs as the pendulum swings between point B and point D. An illustration of a pendulum at 5 different positions. The central position, the equilibrium position is labeled C. The two positions on the left are labeled A and B respectively. The two positions on the right are labeled D and E respectively. All positions are equally spaced. What is the best response that Shari's friend could make? She could agree with Shari because the pendulum is at the same height and would have the same gravitational potential energy at both positions. She could agree with Shari because the pendulum has the same amount of mechanical energy throughout its swing. She could disagree with Shari because the pendulum converts kinetic energy into gravitational potential energy, then back into kinetic energy. She could disagree with Shari because the pendulum converts gravitational potential energy into kinetic energy, then back into gravitational potential energy.
She could disagree with Shari because the pendulum converts gravitational potential energy into kinetic energy, then back into gravitational potential energy.
The arrow for heat is the widest output arrow.
Suchita is going to make an energy transfer diagram to represent the energy transformations associated with the flame of a gas stove. The diagram will show that the chemical energy of the fuel transforms into 50 J of chemical energy, 400 J of heat, and 200 J of light. Which statement describes Suchita's final diagram?
Which is a result of using a machine?
The distance through which a force acts increases, and the force decreases.
On a test, Helena is defining energy. Which must she include in order to get her answer marked correct?
The ability to do work
Suchita is going to make an energy transfer diagram to represent the energy transformations associated with the flame of a gas stove. The diagram will show that the chemical energy of the fuel transforms into 50 J of chemical energy, 400 J of heat, and 200 J of light. Which statement describes Suchita's final diagram?
The arrow for heat is the widest output arrow.
Which statement describes Suchita's final diagram?
The arrow for heat is the widest output arrow.
X: 2 Y: 4 Z: 6
The chart shows data for an object moving at a constant acceleration. Which values best complete the chart?
-1 m
The diagram shows a position-time graph. What is the displacement of the object?
50 meters
The diagram shows two vectors that point west and north. What is the magnitude of the resultant vector?
Every spring has an equilibrium position. Which statements describe a spring at its equilibrium position? Check all that apply.
The elastic potential energy is zero. The displacement of the spring is at a maximum. The net force acting on the spring is zero.
What does it mean when work is positive? Velocity is greater than kinetic energy. Kinetic energy is greater than velocity. The environment did work on an object. An object did work on the environment.
The environment did work on an object.
A load of bricks is lifted to the second floor of a building. How do work and power relate to this job? The longer the job takes, the more work is done. The faster the job is done, the greater the power. The greater the power applied, the more work is done. The less work is done, the more power is needed.
The faster the job is done, the greater the power.
Lamar writes several equations trying to better understand potential energy.
The gravitational potential energy equals the work needed to lift the object.
Which describes how the spring constant affects the potential energy of an object for a given displacement from an equilibrium position?
The higher the spring constant, the greater the elastic potential energy.
Which describes how the spring constant affects the potential energy of an object for a given displacement from an equilibrium position? The higher the spring constant, the greater the gravitational potential energy. The lower the spring constant, the greater the gravitational potential energy. The higher the spring constant, the greater the elastic potential energy. The lower the spring constant, the greater the elastic potential energy.
The higher the spring constant, the greater the elastic potential energy.
The diagram shows a swinging pendulum. Which best explains what happens to the motion of the pendulum?
The mechanical energy transforms to thermal energy as the pendulum slows and eventually stops moving.
by adding vectors that are all the same length and placing them above the current top row of vectors
The motion map shows an object's position and velocity at given times. How can the map be changed so it shows constant acceleration after the object changes direction?
What happens in terms of energy when a moving car hits a parked car, causing the parked car to move?
The moving car transfers kinetic energy to the parked car.
Rita throws a ball straight up into the air and catches it at the same position from which she threw it. The ball has 18 J of mechanical energy when it leaves her hand. If no energy is lost due to friction, which statements about the energy of the ball are true? Check all that apply. The potential energy at the top of the ball's motion is 18 J. The kinetic energy is less when the ball is thrown than when it is caught. The kinetic energy increases as the potential energy decreases. The kinetic energy decreases as the potential energy increases. The total mechanical energy of the ball stays constant. The mechanical energy decreases as the ball moves up and increases as the ball comes down.
The potential energy at the top of the ball's motion is 18 J. The kinetic energy increases as the potential energy decreases. The kinetic energy decreases as the potential energy increases. The total mechanical energy of the ball stays constant.
What is the basis for analyzing an energy transfer diagram? The mechanical energy input and output must be equal. Heat must always be the largest output. The sum of all outputs must equal the input. Electrical energy is an input but not an output.
The sum of all outputs must equal the input.
2
The table shows the mechanical energy and velocity of a rock that was thrown four times. The rock has a mass of 2.4 kg. During which trial was the rock the highest above the ground?
Taro stated that when someone hits a golf ball with a club, the amount of energy the ball has changes, the amount of energy that the club has changes, and the total energy of the system that includes the ball and the club increases. Which best explains Taro's error?
The total energy of the system remains the same.
How do the units of work and power compare? The unit for work is a watt. The unit for power is a joule, which is a watt-second. The unit for work is a watt. The unit for power is a joule, which is a watt per second. The unit for work is a joule. The unit for power is a watt, which is a joule-second. The unit for work is a joule. The unit for power is a watt, which is a joule per second.
The unit for work is a joule. The unit for power is a watt, which is a joule per second.
Which statements correctly compare the work done to move the couches? Check all that apply.
The work for couch 2 is less than the work for couch 3. The work for couch 3 is greater than the work for couch 1. The work for couch 2 is greater than the work for couch 1.
How does the work needed to lift an object and the gravitational potential energy of the object compare?
They are equal.
How does the work needed to lift an object and the gravitational potential energy of the object compare? They are equal. The work is greater. The work is less. The comparison depends on the height.
They are equal.
Energy is the ability to _____________________.
To do work, produce heat, cause change
High-energy gamma rays are directed at a tumor from outside of the body. Gamma rays kill cancer cells in a tumor
Which statements describe the use of gamma rays to treat cancer? Check all that apply.
The use of force to move an object is
Work
Suppose an object's initial velocity is 10 m/s and its final velocity is 4 m/s. Mass is constant. What can best be concluded about the object based on the work-energy theorem?
Work is negative, the object did work on the environment, and the energy of the system decreases.
The diagram shows a side view of a skateboard ramp. At which labeled points would the skateboarder have the most kinetic energy?
X and Y
The diagram shows a side view of a skateboard ramp. At which labeled points would the skateboarder have the most kinetic energy? W and X X and Y Y and Z W and Z
X and Y
The chart shows data for four different moving objects. Which shows the order of the objects' kinetic energies, from least to greatest? W, Y, X, Z Z, X, Y, W W, Y, Z, X X, Z, Y, W
X, Z, Y, W
Which activity directly converts energy from the Sun into chemical energy?
a bean plant making its own food to grow
Four different balls are moving at the same velocity. Which will have the greatest kinetic energy as it rolls?
a bowling ball
Which best identifies the requirements for work to be performed? an object that has a force acting on it an object that is moving and has no net force a force acting on a motionless object a force that moves an object
a force that moves an object
spring constant
a measure of the springs resistance to being compressed or stretched, the measure of the stiffness of the spring
Four vehicles are traveling on the same road. Which vehicle most likely has the greatest kinetic energy? a compact car traveling at a velocity of 10 m/s a pickup truck traveling at a velocity of 25 m/s a minivan traveling at a velocity of 10 m/s a motorcycle traveling at a velocity of 25 m/s
a pickup truck traveling at a velocity of 25 m/s
work
a scalar quantity that has a positive or negative sign
When energy is changed from one form to another, some of the energy is lost to the surroundings as waste thermal energy. The more steps needed to arrive at the desired energy or the more types of energy that are generated, the more energy is wasted. Which object would likely have the least amount of wasted energy? a hairdryer a solar cell a car engine a hydroelectric dam
a solar cell
A wheelbarrow can be used to help lift a load, such as a pile of dirt, and then push the load across a distance. Which simple machines make up a wheelbarrow?
a wheel and axle and a lever
Lester prepares to lift a heavy sack of flour into a customer's shopping cart. During which part of the action does Lester do work? when he applies force to the sack before lifting it when he holds the sack against his chest as he lets go of the sack and it falls onto a cart as he lifts the sack to his chest from the floor
as he lifts the sack to his chest from the floor
lamar
b
Which change would cause the largest increase in a mountain climber's gravitational potential energy?
carrying twice the weight and climbing twice as high
Which change would cause the largest increase in a mountain climber's gravitational potential energy? carrying twice the weight and climbing half as high carrying half the weight and climbing half as high carrying twice the weight and climbing twice as high carrying half the weight and climbing twice as high
carrying twice the weight and climbing twice as high
A force of 75 N at an angle of 15° to the direction of motion moves a chair 3 m. Which change would result in more work being done on the chair? using 60 N of force moving the chair 2 m increasing the angle to 20° decreasing the angle to 10°
decreasing the angle to 10°
What is the sequence of energy transformations associated with a hydroelectric dam? electrical energy into mechanical energy into kinetic energy into gravitational potential energy gravitational potential energy into kinetic energy into mechanical energy into electrical energy chemical energy into kinetic energy into mechanical energy into electrical energy chemical energy into thermal energy into kinetic energy into electrical energy
gravitational potential energy into kinetic energy into mechanical energy into electrical energy
Johanna is studying what happens to the energy as a ball rolls down a ramp. What is she studying? Check all that apply.
gravitational potential energy, kinetic energy, mechanical energy
what are the two forms of mechanical potential energy?
gravitational potential energy,elastic potential energy
elastic potential energy
is the energy stored in a compressed or stretched object, such as a spring
what is the unit of work?
joule,J
Energy can be transformed from one form to another. The diagram shows one such process. Which energy transformation is represented in the diagram?
nuclear to thermal and radiant
The stored energy an object has due to its position is ____ energy.
potential
The stored energy an object has due to its position is _____________ energy.
potential
The stored energy an object has due to its position is _________________ energy.
potential
A flashlight uses the chemical energy stored in a battery. This chemical energy is eventually converted into which two forms of energy?
radiant and thermal
Ray creates an energy transfer diagram for a hair dryer. However, the diagram contains an error that could be corrected in several different ways. An illustration of a hair dryer with a wide arrow pointing away from it labeled electrical energy 750 J that splits into three arrows labeled kinetic energy 125 J, sound energy 150 J, and thermal energy 550 J. Which of these changes would make the diagram error-free? Check all that apply. reducing the amount of thermal energy to 475 J increasing the amount of electrical energy to 825 J increasing the amount of sound energy to 225 J reducing the amount of kinetic energy to 50 J reducing the amount of electrical energy to 675 J
reducing the amount of thermal energy to 475 J increasing the amount of electrical energy to 825 J reducing the amount of kinetic energy to 50 J
Read each scenario and then answer the questions. Scenario A: A shopping cart is pushed a distance of 3 m by a force of 15 N. Scenario B: A shopping cart is pushed a distance of 4 m by a force of 12 N. Scenario C: A shopping cart is pushed a distance of 6 m by a force of 10 N. Which scenario requires the most work? Which scenario requires the least work?
scenario C requires the most work scenario A requires the least work