AP Physics 1 : Linear Motion and Momentum

Study concepts, example questions & explanations for AP Physics 1

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Example Questions

Example Question #311 : Linear Motion And Momentum

The position of a particle can be described by:

The position is measured in , and the time is in . What is the average velocity for the particle in the time interval ?

Possible Answers:

Correct answer:

Explanation:

You can think of the average velocity of a particle as the difference between the final and initial states. Conventionally, we call this slope. Therefore, we need to plug in our two initial times into the position function, and use the equation for slope between two points to determine the average velocity.

Therefore, our two coordinates are: 

Now, we use the slope equation:

Example Question #311 : Linear Motion And Momentum

A  woman has a jet pack that has a mass of . She ignites the jet pack and it accelerates her at a rate of . Determine the time it took to reach a height of .

Possible Answers:

None of these

Correct answer:

Explanation:

Using the kinematic equation:

Example Question #581 : Ap Physics 1

 woman has a jet pack that has a mass of . She ignites the jet pack and it accelerates her at a rate of . Determine her velocity at the moment she reaches a height of .

Possible Answers:

None of these

Impossible to determine

Correct answer:

Explanation:

Using the kinematic equation:

Using

Example Question #41 : Fundamentals Of Displacement, Velocity, And Acceleration

 woman has a jet pack that has a mass of . She ignites the jet pack and it accelerates her at a rate of . Determine her kinetic energy at a height of .

Possible Answers:

None of these

Correct answer:

Explanation:

Initially she is at rest.

Combining equations:

Solving for 

Plugging in values:

Using 

Example Question #41 : Fundamentals Of Displacement, Velocity, And Acceleration

A woman with a jet pack is  above the ground. She drops a ball. If she waits until  after she dropped the ball to accelerate downward to try and catch it, how fast will she have to accelerate to reach it at a height of ?

Possible Answers:

None of these

Correct answer:

Explanation:

Distance fallen by ball:

Distance fallen by woman:

Both distances need to be 

If it fell 

Since she waits  to drop, 

Combining equations:

Solving for 

Acceleration will be gravity

Example Question #316 : Linear Motion And Momentum

Four strings are used to hold up a  puppet, motionless. Determine the tension in each string.

Possible Answers:

None of these

Correct answer:

Explanation:

Assuming all tensions will be equal

The puppet is not moving

Using 

Solving for 

Plugging in values

Example Question #317 : Linear Motion And Momentum

A man with a jet pack is  above the ground. He drops a ball. If he waits until  after he dropped the ball to accelerate downward to try and catch it, how fast will he have to accelerate to reach it at a height of ?

Possible Answers:

None of these

Correct answer:

Explanation:

In order for the ball to reach a height of , it would need to fall a distance of . Using

The initial velocity is zero, and the initial distance can be taken as zero as well.

Solving for time

This is the time the ball takes to fall to a height of .

The man with the jet pack will have:

Again, using

Again, 

Initial velocity is zero, and the initial distance can be taken as zero as well.

Example Question #311 : Linear Motion And Momentum

A car is stopped at a red light. When the light turns green, it accelerates uniformly at a rate of . How fast is the car traveling after  seconds?

Possible Answers:

 

Correct answer:

 

Explanation:

Acceleration is defined as a change in velocity over time:

Since the car is initially at rest at the stop light, . The acceleration is given as and the problem is asking for the velocity at . Therefore,

Example Question #311 : Linear Motion And Momentum

A train travels in  hour. What is the train's average speed in units of meters per second?

Possible Answers:

Correct answer:

Explanation:

Average velocity is defined as distance over time. Therefore, the train is traveling at an average rate of . However, this problem asks for the answer to be in units of . Here is an efficient way to convert the units using dimensional analysis:

Example Question #41 : Fundamentals Of Displacement, Velocity, And Acceleration

Madison enters an elevator on the ground floor of a building. She selects the button for the fifth floor and the elevator doors close. The elevator accelerates for  seconds until it reaches a constant velocity for  seconds, and then decelerates for  seconds before stopping at the fifth floor.

What direction is the acceleration  seconds into Madison's elevator ride?

Possible Answers:

The acceleration is in the upward direction.

The acceleration is in the downward direction.

The acceleration is to the left.

The acceleration is zero.

The acceleration is to the right.

Correct answer:

The acceleration is zero.

Explanation:

At  seconds, the elevator is traveling at a constant velocity. When the velocity is constant, acceleration is zero. This can be confirmed using the equation for acceleration:

When there is no change in  (constant velocity), then the numerator is zero. Thus, .

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