AP Physics 1 : AP Physics 1

Study concepts, example questions & explanations for AP Physics 1

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Example Questions

Example Question #182 : Work, Energy, And Power

A ball is thrown directly upwards from a height of at . Determine the maximum height.

Possible Answers:

None of these

Correct answer:

Explanation:

Using

Assuming that the system is closed and no work is done:

Solving for

At the maximum height, the ball will be stopped, and have a velocity of

Plugging in values:

Example Question #41 : Conservation Of Energy

A  box falls from a height of  onto a spring with spring constant . What is the compression of the spring?

Possible Answers:

Correct answer:

Explanation:

This question relies on the conservation of energy. Potential energy is represented by , while potential spring energy can be written as . Due to the conservation of energy, the two equations must be set equal to each other and rearranged so that x is isolated. 

Example Question #181 : Work, Energy, And Power

A sports car traveling at  will require  to come to a complete stop with locked brakes. How far will the shinny sports car skid in meters of stopping distance if it was originally traveling at 

Possible Answers:

Correct answer:

Explanation:

For this question we will use the conservation of energy. Thus the kinetic energy of the initial situation is proportional to the kinetic energy of the second situation.

The mass does not change. 

There is a  fold increase in the speed. The velocity value is squared in the kinetic energy equation.

The stopping distance must be multiplied a factor of .

The sports car will now require  to come to a complete stop.

Example Question #182 : Work, Energy, And Power

Tim was taking a practice physics test sitting at an elevated bar top at his house. Tim's brother came down the stairs and scared Tim causing him to knock his calculator off the bar top. If the calculator has a mass of  what is the total kinetic energy of the calculator right before it contacts the hard tile floor below? 

Possible Answers:

Correct answer:

Explanation:

Use the conservation of energy to solve.

The calculator will have  of kinetic energy before it contacts the ground.

Example Question #41 : Conservation Of Energy

At a large shipyard in the Atlantic ocean, cranes lift large cargo boxes off of incoming ships. Some of these cargo boxes have a staggering mass near that of . These cranes will then lift these boxes to a height of  off the ground. If the cable attached to the cargo boxes were to break when the box was at half it's expected height, at what final velocity will the cargo box be traveling right before it contacts the ground below?

Possible Answers:

Correct answer:

Explanation:

For this question you may use one of two main methods. For this example, the conservation of energy method is shown.

Initially, all the energy is stored as gravitational potential energy. At the end of the fall all of the energy will be transformed to kinetic energy.

Plug in and solve for the final velocity.

The large cargo box will be traveling at  right before it contacts the ground below.

Example Question #45 : Conservation Of Energy

Rollercoaster

The height at the top of the hill is 

If the velocity of the train at the top of the loop is , how high is the highest point of the loop?

Possible Answers:

Correct answer:

Explanation:

Due to conservation of energy, all energy is conserved throughout this problem. When the train is at the top of the hill, all energy is stored in the form of gravitational potential energy, represented by the equation:

Once the train starts rolling down the hill some of that energy gets transferred to kinetic energy, which is represented by the equation:

Because you are given the velocity at the top of the loop it is possible to find the height of the loop by connecting the two equations as follows:

Where  is the height at the top of the hill, and  is the height at any given point in the system. By plugging in the given values and cancelling out the  for mass on both sides of the equation, it is possible to find the height at the top of the loop as follows:

Example Question #46 : Conservation Of Energy

Rollercoaster

The following roller coaster has a height at the top of the hill of  and a height at the top of the loop of . It is moving at a velocity of  at the top of the hill. 

What is the velocity of the train car at the top of the loop?

 

Possible Answers:

Correct answer:

Explanation:

Energy must be conserved throughout this problem. The kinetic energy plus the potential energy must be the same at any point on the track. Kinetic energy and potential energy are represented by the following equations:

 

where  is mass,  is height, and  is velocity.

Since these equations combined must be equal at any point in the track, they can be put together in order to figure out the height at the top of the loop.

Where  is the top of the hill and  is at the top of the loop. Given values can now be plugged in, in order to find the velocity at the top of the loop. Because mass is present in each part of the equation, mass can be cancelled out and ignored.

Example Question #183 : Work, Energy, And Power

Rollercoaster 2

The following train car has a velocity of  and is travelling to the left.

How far up the hill will the car travel before stopping and starting to roll back down?

Possible Answers:

Correct answer:

Explanation:

Energy must be conserved throughout this entire problem. Kinetic energy and potential energy are represented by the following equations:

Since the train car at the bottom of the hill has no height, all of the energy is in the form of kinetic energy. Because the problem is asking for the height on the track at which the train car stops moving, there is no velocity at that point, therefore all the energy is in the form of potential energy. Since energy is conserved, the kinetic energy at the bottom of the hill must be equal to the potential energy at the point where the train car stops. The following equation can be made to find the height at that point:

where  is the point at the bottom of the track and  is the point on the hill where the train stops rolling. Given values can now be plugged in in order to find the height. Since mass is on both sides, it can be cancelled out.

 

Example Question #48 : Conservation Of Energy

A funny car goes from rest to  in . If the car has a  "tank to track" efficiency, determine how much energy from the fuel tank was used.

Possible Answers:

None of these

Correct answer:

Explanation:

Since the initial velocity is zero, initial kinetic energy is zero

Plugging in values:

Example Question #41 : Conservation Of Energy

A ball initially rest at the top of a hill beings rolling down the hill. 

Which of the following answer choices is true? 

Possible Answers:

Total energy at the top of the hill equals total energy at the bottom of the hill

The total energy is never constant 

The total energy at the top of the hill is greater than the total energy at the bottom of the hill

The total energy depends on the mass of the ball

The total energy at the bottom of the hill is greater than the total energy at the top of the hill 

Correct answer:

Total energy at the top of the hill equals total energy at the bottom of the hill

Explanation:

The correct answer is that the total energy at the top of the hill is equal to the total energy at the bottom of the hill. This is called the Law of Conservation of Energy. This law says that kinetic energy is equal to potential energy. We know that energy can not be created or destroyed, but that it can be transferred from one type to another. The total energy at the top of the hill is all potential energy. As the ball begins rolling down the hill, all the potential energy is converted to kinetic energy. Therefore, the total energy remains constant and energy is conserved.  

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