NG8-3

A boy was riding his bike on a level road.  He stopped pedaling and applied the brakes.  When he applied the brakes, the brake pads squeezed the wheel, and the bike slowed down and stopped.  After the bike stopped, the brake pads had more thermal energy.  Why did the thermal energy of the brake pads increase?

A.		Because some of the motion energy (kinetic energy) that the bike and the boy had was converted into thermal energy of the brake pads
B.		Because the energy that was stored inside of the brake pads was released in the form of thermal energy when the bike stopped
C.		Because some of the thermal energy that the boy had was converted into thermal energy of the brake pads
D.		Because new energy was made in the form of thermal energy in the brake pads

NG82-3

A scientist determines the total amount of energy an apple has while it is hanging on a tree.  The apple falls from the tree to the ground.  The scientist determines that the apple has less energy when it is on the ground than it did when it was on the tree.  What happened to the energy of the apple?

A.		Some of the energy the apple had when it was on the tree was transferred somewhere else, like the ground or the air, because whenever energy is lost from somewhere, it must have gone somewhere else.
B.		Some of the energy the apple had when it was on the tree was changed into a force when it hit the ground because the energy of moving objects is changed into forces whenever objects hit each other.
C.		Some of the energy the apple had when it was on the tree was used up as the apple fell because energy is used up anytime an object moves.
D.		The apple no longer has any energy because the apple can only have energy when it is attached to the tree.

NG24-2

The temperature of a plastic block is 60ºF, and the temperature of a metal block is 40ºF.  The student puts the plastic block on top of the metal block.  Will the blocks ever be at the same temperature and why?

A.		Yes, but only for a little while because the metal block will continue to get warmer and the plastic block will continue to cool
B.		Yes, because thermal energy will be transferred from the plastic block to the metal block until they reach the same temperature
C.		No, because the temperature difference is not large enough for thermal energy to be transferred
D.		No, because the blocks are made of different materials

NG12-2

A rubber ball speeds up as it falls from Position 1 toward the floor.  The ball is compressed as it hits the floor (Position 2) and then returns to its original shape as it bounces back up into the air (Position 3).

What happens to the elastic energy of the ball as it moves from Position 2 to Position 3?

A.		New energy is made in the form of elastic energy.
B.		The elastic energy of the ball is converted into motion energy (kinetic energy) and gravitational potential energy.
C.		The elastic energy of the ball is used up.  It is not converted into any other form of energy.
D.		The elastic energy of a rubber ball cannot change, and, therefore, nothing happens to the elastic energy of the ball when it moves from Position 2 to Position 3.

NG76-3

Which of the following statements about the total amount of energy in a system is TRUE?

A.		The total amount of energy in a system always increases when the objects in the system are moving.
B.		The total amount of energy in a system always decreases regardless of what forms of energy are present in the system.
C.		The total amount of energy in a system remains the same unless energy enters or leaves the system.
D.		The total amount of energy in a system can change even when no energy enters or leaves the system, but the forms of energy present in the system must remain the same.

NG30-3

A person takes food out of a hot oven and lets it cool on the counter.  The food has less energy when it is cool.  Which of the following describes what happened to the energy of the food?

A.		Energy (in the form of thermal energy) was transferred to the things the food is touching, such as the air and the counter, and energy (in the form of electromagnetic radiation) was transferred to things the food is not touching, such as the kitchen walls.
B.		Energy (in the form of thermal energy) was transferred only to the things the food is touching, such as the air and the counter.
C.		Energy (in the form of electromagnetic radiation) was transferred only to things the food is not touching, such as the kitchen walls.
D.		No energy was transferred to the things the food is touching, such as the air and the counter, or to things the food is not touching, such as the kitchen walls.  The energy just disappeared as the food cooled.

NG100-1

A ball is falling towards the ground.  The speed of the ball increases as it falls.  While the ball is falling and before it hits the ground, which of the following forms of energy is the gravitational potential energy of the ball being transformed into?  (Assume that the ball is not stretched or compressed when it is traveling through the air.)

A.		Both the motion energy (kinetic energy) of the ball and the elastic energy of the ball
B.		The motion energy (kinetic energy) of the ball but not the elastic energy of the ball
C.		The elastic energy of the ball but not the motion energy (kinetic energy) of the ball
D.		Neither the elastic energy of the ball nor the motion energy (kinetic energy) of the ball

NG61-2

A cook heats an ear of corn in a pot of hot water.  She takes the corn out of the hot water and puts it on a plate.  Then she takes some butter out of the refrigerator.  She cuts a piece of cold butter and places it on top of the hot corn.

Which of the following describes how thermal energy is transferred between the corn and the butter?

A.		Thermal energy is transferred both from the corn to the butter and from the butter to the corn.
B.		Thermal energy is transferred from the corn to the butter but not from the butter to the corn.
C.		Thermal energy is transferred from the butter to the corn but not from the corn to the butter.
D.		Thermal energy is not transferred between the corn and the butter.

NG96-2

Imagine a ball on a track where no energy is transferred between the ball and the track or between the ball and the air around it.  The ball starts at Position 1 and goes down and up a dip on the track and past Position 2.  Position 1 and Position 2 are at the same height.

Will the total amount of energy the ball has at Position 2 be more, less, or the same as the total amount of energy the ball has at Position 1 and why?  (Remember that no energy is transferred between the ball and the track or between the ball and the air around it.)

A.		The total amount of energy the ball has will be more at Position 2 because new energy was made when the ball went down the steep side of the dip.
B.		The total amount of energy the ball has will be less at Position 2 because energy was used up when the ball went up the long side of the dip.
C.		The total amount of energy the ball has will be the same at Position 1 and Position 2 because the total amount of energy in the system (ball and track) did not change.
D.		Whether the total amount of energy of the ball is more, less, or the same at Position 2 compared to Position 1 depends on the speed of the ball before it got to the dip.

NG57-2

Consider the following situations:

Situation 2: A lamp shines light on a table.

Is energy being transferred in either of these situations?

A.		Energy is transferred in both situations.
B.		Energy is NOT transferred in either situation.
C.		Energy is transferred when a person touches a cold piece of metal, but energy is NOT transferred when a lamp shines light on a table.
D.		Energy is transferred when a lamp shines light on a table, but energy is NOT transferred when a person touches a cold piece of metal.

NG81-3

In the morning, a student puts a warm can of soda in a cooler filled with ice.

He closes the cooler.  At lunch, the can of soda is colder.  What happened to the total amount of energy in the cooler containing the can of soda and the ice?  (Assume that no energy is transferred into or out of the cooler when it is closed.)

A.		The total amount of energy increased because the energy that the can of soda transferred to the ice is greater than the energy that the ice lost.
B.		The total amount of energy decreased because the can of soda has less energy than it started with, and the amount of energy the ice has did not change.
C.		The total amount of energy stayed the same because the amount of energy that the can of soda lost is equal to the amount of energy that the ice gained.
D.		The total amount of energy stayed the same because being warmer or colder does not affect the amount of energy objects have.

NG9-5

A boy holds a book above the floor.  He lets go of the book and the book speeds up as it falls to the floor.  Which of the following forms of energy are involved in an energy transformation while the book is falling?  Why?

A.		Both gravitational potential energy and motion energy (kinetic energy) are involved.  As the book is falling, its gravitational potential energy decreases and its motion energy is increases.
B.		Gravitational potential energy is involved but motion energy (kinetic energy) is not.  As the book is falling, its gravitational potential energy decreases but its motion energy does not change.
C.		Motion energy (kinetic energy) is involved but gravitational potential energy is not.  As the book is falling, its motion energy increases but its gravitational potential energy does not change.
D.		Neither gravitational potential energy nor motion energy (kinetic energy) is involved.  Gravitational potential energy cannot be changed into motion energy, and motion energy cannot be changed into gravitational potential energy.

NG39-2

A radiator is a device used to heat up a room.  When a student stands near the radiator, he feels warm even though he is not touching the radiator. 

What will happen if the student holds a blanket up so that the blanket is between himself and the radiator?

A.		He will feel warmer because blankets are used to keep people warm.
B.		He will feel cooler because the blanket is blocking the energy being given off by the radiator.
C.		He will feel the same because the temperature of the air in the room will not change.
D.		He will feel the same because he is still receiving the same amount of energy from the radiator.

NG83-3

A cook heats up some food on a stove.  He removes the food from the stove and places it on a plate.  He lets the food cool.  The food has less energy when it is cool.  His friend tells him that some of the energy was transferred to the air around the food.  The cook does not agree with his friend because the temperature of the air around the food did not seem to increase.  Is the friend correct in saying that some of the energy was transferred to the air, and why or why not?

A.		No, the energy could not have been transferred to the air because energy cannot be transferred from one object to another.
B.		No, even though energy can be transferred from one object to another, the energy could not have been transferred to the air because air is not an object.
C.		No, the energy could not have been transferred to the air because all of the energy was used up when the food cooled down.
D.		Yes, even though the temperature of the air did not appear to increase, some of the energy could have been transferred to the air because energy is always conserved.  The increase in the air's energy is just difficult to detect.

 

NG79-2

A girl shoves a book, and it slides across a table.  The book slows down and then stops.  As the book moves, the book and the table get a little bit warmer.  What happened to the motion energy (kinetic energy) of the book?

A.		It was transformed into a force but not into thermal energy.
B.		It was transformed into thermal energy but not into a force.
C.		It was transformed into both a force and thermal energy.
D.		It was used up and was not transformed into a force or thermal energy.

NG49-3

After he lets go of the cart, the spring pushes the cart and the cart rolls across the floor. 

    

Which of the following graphs represents the elastic energy of the spring and the motion energy (kinetic energy) of the cart when the cart is rolling across the floor and the spring is no longer in contact with the cart?  (Assume that no energy is transferred between the spring and its surroundings and no energy is transferred between the cart and its surroundings.)

     

NG74-3

Imagine a ball on a track where no energy is transferred between the ball and the track or between the ball and the air around it.  The ball starts from rest at the position labeled Start and moves along the track toward Positions 1, 2, 3, and 4.

What is the highest position the ball will reach before stopping and going back down the track?  Why?  (Remember that no energy is transferred between the ball and the track or between the ball and the air around it.)

A.		Position 1.  The total amount of energy the ball has will decrease as it moves along the track, and it will not have enough energy to make it over the hill.
B.		Position 2.  The total amount of energy the ball has will decrease as it moves along the track, but it will still have enough energy to make it over the hill and reach a position a little lower than the position it started from.
C.		Position 3.  The total amount of energy the ball has will not change as it moves along the track, so the ball will reach a position that is the same height as the position it started from.
D.		Position 4.  The total amount of energy the ball has will increase as the ball moves along the track, so it will have enough energy to make it over the hill and reach a position a little higher than the position it started from.

NG5-3

A boy holds a piece of clay above the floor.  After he drops the clay, it speeds up as it falls.  As it hits the floor, the clay flattens and gets a little warmer.

Which of the following describes the changes in the energy of the clay ball?

A.		As the clay falls, its gravitational potential energy is converted to motion energy (kinetic energy).  As it hits the floor, its motion energy (kinetic energy) is converted to thermal energy.
B.		As the clay falls, its motion energy (kinetic energy) is converted to gravitational potential energy.  As it hits the floor, its gravitational potential energy is converted to thermal energy.
C.		As the clay falls, its gravitational potential energy is converted to motion energy (kinetic energy).  As it hits the floor, its motion energy (kinetic energy) is used up but is not converted into thermal energy.
D.		As the clay falls, its motion energy (kinetic energy) is converted to gravitational potential energy.  As it hits the floor, its gravitational potential energy remains the same and is not converted into thermal energy.

NG22-3

The temperature of a plastic cup is 70ºF.  It is then filled with water that is 40ºF.  Which of the following describes how thermal energy is transferred?

A.		Thermal energy is transferred from the water to the cup until they are both at 45ºF.
B.		Thermal energy is transferred from the cup to the water until they are both at 45ºF.
C.		Thermal energy is transferred from the cup to the water until the cup is at 60ºF and the water is at 50ºF.
D.		No thermal energy is transferred between the cup and the water, so the cup will stay at 70ºF and the water will stay at 40ºF.

NG86-2

An engineer is building a roller coaster and wants the roller coaster car to go over two hills.  In order for the roller coaster car to make it over both hills, should the first hill be higher or lower than the second hill?  (Assume that no energy is transferred between the roller coaster car and the track or between the roller coaster car and the air around it.)

A.		The first hill has to be higher than the second hill because the roller coaster car will lose energy as it rolls along the track, so it will not be able to get over a second hill that is as high as the first hill.
B.		The first hill can be lower than the second hill because the roller coaster car will gain enough energy as it rolls along the track to get over a second hill that is higher than the first hill.
C.		It doesn't matter which hill is higher as long as they are both lower than the starting point because no energy is lost as the roller coaster car rolls along the track, so it can get over any hill that is lower than the starting point.
D.		It doesn't matter which hill is higher because even though the total amount of energy that the roller coaster car has will decrease going uphill, it will increase enough going downhill to get over any size hill.

NG4-3

Is energy transformed while a rock is falling from a cliff?  Explain.

A.		Yes, motion energy (kinetic energy) is transformed into gravitational potential energy as the rock falls.
B.		Yes, gravitational potential energy is transformed into motion energy (kinetic energy) as the rock falls.
C.		No, because the rock lost all of its gravitational potential energy once it started to move.
D.		No, because one form of energy cannot be transformed into another form of energy.

NG35-2

When do the heating coils on an electric stove give off energy in the form of electromagnetic radiation?

A.		Only when they are too hot to touch
B.		Only when they are so hot that they are glowing
C.		The coils give off energy in the form of electromagnetic radiation at all temperatures.
D.		The coils do not give off energy in the form of electromagnetic radiation at any temperature.

NG88-3

A student stretches a rubber band.  The graph shows the amount of elastic energy the rubber band has before he lets go of it.  The graph also shows the amount of motion energy (kinetic energy) the rubber band has before he lets go of it and the total amount of elastic and motion energy in the system.

The student lets the rubber band go and it flies across the room.  Which of the following graphs represents the elastic energy, motion energy, and total amount of elastic and motion energy of the rubber band as it flies across the room and is no longer stretched?  (We are assuming that no energy is transferred between the rubber band and the air around it and that any changes in the thermal energy and gravitational potential energy of the rubber band are so small that they can be ignored.)

NG16-3

A ball is rolling up and over a hill.  The ball slows down as it moves from Position 1 to Position 3, and it speeds up as it moves from Position 3 to Position 5.

When is the gravitational potential energy of the ball being transformed into motion energy (kinetic energy)?

A.		Only when the ball rolls from Position 1 to Position 3
B.		Only when the ball rolls from Position 3 to Position 5
C.		The entire time the ball is rolling from Position 1 to Position 5
D.		It is not being transformed at any time because gravitational potential energy cannot be transformed into motion energy (kinetic energy).

NG26-3

A student is holding a cold piece of metal in her hand.  While she is holding the piece of metal, her hand gets colder.  Does the piece of metal get warmer or colder and why?

A.		Colder, because all objects give off thermal energy all the time and gradually cool down
B.		Warmer, because some thermal energy is transferred from cold objects to warm objects when the objects are touching each other
C.		Warmer, because some thermal energy is transferred from warm objects to cold objects when the objects are touching each other
D.		Neither, the metal will stay at the same temperature because an equal amount of thermal energy is exchanged between warm objects and cold objects when the objects are touching each other.

NG93-2

Imagine a ball on a track where no energy is transferred between the ball and the track or between the ball and the air around it.  It is going fast enough at Position 1 so that it will go over a hill on the track and past Position 2.  Position 1 and Position 2 are at the same height.

Will the total amount of energy the ball has at Position 2 be more, less, or the same as the total amount of energy the ball had at Position 1 and why?  (Remember that no energy is transferred between the ball and the track or between the ball and the air around it.)

A.		The total amount of energy the ball has will be more at Position 2 because new energy was made when the ball went down the long side of the hill.
B.		The total amount of energy the ball has will be less at Position 2 because energy was used up when the ball went up the steep side of the hill.
C.		The total amount of energy the ball has will be the same at Position 1 and Position 2 because the total amount of energy in the system (ball and track) did not change.
D.		Whether the total amount of energy of the ball is more, less, or the same at Position 2 compared to Position 1 depends on the speed of the ball before it got to the hill.

NG41-2

A cook heats a piece of bread in a toaster.  He turns off the toaster but leaves the bread inside of it.  Is energy being transferred by radiation from the toaster to the bread even when the toaster is turned off?  Why or why not?

A.		Yes, because all objects radiate energy at all times
B.		Yes, because only objects that are used to heat things radiate energy at all times
C.		No, because only fire radiate energy
D.		No, because only objects that are glowing radiate energy

NG11-3

A student shoves a box, and it slides across the floor.  As the box slides across the floor, the box slows down and both the box and the floor get a little warmer.  What happens to the energy of the box as it slides across the floor and comes to a stop and why?

A.		The motion energy (kinetic energy) of the box decreases and its thermal energy increases because the motion energy is converted into thermal energy.
B.		The motion energy (kinetic energy) of the box decreases and its thermal energy stays the same because motion energy is used up and is not converted into thermal energy.
C.		The motion energy (kinetic energy) of the box stays the same and its thermal energy increases because new energy in the form of thermal energy is made.
D.		Both the motion energy (kinetic energy) and the thermal energy of the box decrease to zero because the box is no longer moving and an object has energy only when it is moving.

NG63-3

A person takes a cold bottle of water out of the refrigerator and places it in a small empty cabinet.  The person closes the cabinet door.  What will happen to the temperature of the bottle of water and the temperature of the air in the cabinet and why?

A.		The temperature of the bottle of water will increase and the temperature of the air in the cabinet will decrease because energy will be transferred from the bottle to the air.
B.		The temperature of the bottle of water will increase because new energy will be made as the bottle warms up, but the temperature of the air in the cabinet will not change because the temperature of air cannot change.
C.		The temperature of the bottle of water will not change because it will not lose any energy, and the temperature of the air in the cabinet will decrease because coldness will be transferred from the bottle to the air.
D.		The temperature of the bottle of water and the temperature of the air in the cabinet will not change because no energy is transferred between the air and the bottle.

 

NG80-3

A boy holds a ball of clay above the floor.  He lets go of the clay ball, and it speeds up as it falls to the floor.  The clay ball flattens as it hits the floor and remains flat.  When the clay ball hits the floor, the ball and the floor get a little warmer.  (Assume that no energy is transferred between the clay ball and the air or between the floor and the air.)

As the clay ball falls and hits the floor, does the total amount of energy in the system (the clay ball and the floor) increase, decrease, or stay the same?  Why?

A.		The total amount of energy in the system increases because the clay ball and the floor are warmer, and therefore, have more energy.
B.		The total amount of energy in the system decreases.  Although the energy of the clay ball and the floor increases as they get warmer, the energy of the clay ball decreases by an even greater amount as it moves closer to the ground.
C.		The total amount of energy in the system stays the same because the decrease in energy due to the clay ball moving closer to the ground is equal to the increase in energy due to the clay ball and the floor getting warmer.
D.		The total amount of energy in the system stays the same.  Even though the clay ball and the floor are warmer, being warmer is not associated with the amount of energy an object has.

NG33-3

A girl is sitting under an umbrella at the beach on a sunny day.  When she moves out of the shade and into the sunlight, she will feel warmer.  Why?

A.		Because energy is being transferred directly from the sun to the girl
B.		Because energy is being transferred from the sun to the air and then from the air to the girl, but no energy is being transferred directly from the sun to the girl
C.		Because energy is being transferred from the sun to the ground and then from the ground to the girl, but no energy is being transferred directly from the sun to the girl
D.		Because the sun is shining on the girl, not because energy was transferred from the sun to the girl