# High School Physics : Understanding Motion in One Dimension

## Example Questions

### Example Question #21 : Motion And Mechanics

A ball rolls at . Assuming no outside forces, how long will it take to roll ?

Explanation:

The relationship between distance, velocity, and time is given by the equation for velocity:

We can rearrange this formula for solve for the time.

Using the given values for the velocity and distance traveled, we can solve for the time.

### Example Question #22 : Motion And Mechanics

A ball begins to roll with a velocity of . If it has an acceleration of  and rolls for , what is the final velocity?

Explanation:

For this question, we will need to use the acceleration formula:

We are given the initial velocity, acceleration, and time. Using these values in the equation, we can solve for the final velocity.

### Example Question #91 : High School Physics

A stone is thrown downward with a speed of  from a height of 15m. What is the speed of the stone just before it collides with the ground?

Explanation:

To solve this problem we use a kinematic equation that relates the square of the final velocity to the sum of the initial velocity squared and the change of position.

All values needed to find the final velocity are given, plug them in and solve.

### Example Question #92 : High School Physics

An object is dropped from the roof of a building, how fast is it traveling after 9s? How far would it have fallen? Assume the building is tall enough for the object to have not hit the ground during this time and neglect air resistance.

Explanation:

The only force accelerating the object is gravity since it was dropped, not thrown. Thus, to find out the speed of the object after some time, simply multiply the time the object has fallen by the acceleration of gravity. We will use . Then use the average velocity to calculate the distance the phone fell.

Final velocity after 9s:

Distance the phone has fallen during the 9s of free fall:

### Example Question #93 : High School Physics

If Bob threw an orange straight up with an initial velocity of , what height would the orange reach? Disregard the height it Bob's your hand.

None of these

Explanation:

Use a kinematic equation. Select the correct one by variables we have or do not have. We were given initial velocity, we know the final velocity will be zero because the orange has to hit the ground, and we know the acceleration of gravity. These parameters fit closest with the equation:

Plug in the variables we know or were given:

Solve for vertical displacement:

### Example Question #94 : High School Physics

A remote control car accelerates from rest across a parking lot at  and does so for 12s. What distance did it travel during this time?

Explanation:

Use a kinematic equation. Based on the variables we were given, the best equation to use is:

and . We know initial velocity is 0 because it started from rest. Plug in known values:

The red term becomes 0.

Solve for horizontal displacement:

### Example Question #95 : High School Physics

You are trying to determine the height of water in a well by dropping a rock into it. If you hear it hit the water after 6s, what is the distance to the surface of the water? Ignore friction.

None of these

None of these

Explanation:

Based on the variables given select the appropriate kinematic equation. We only know gravity and time, but we need to solve for distance.

The red term becomes 0 because the rock was dropped. Its initial velocity is 0.

### Example Question #21 : Linear Motion

A person base jumps off a tall mountain peak and freefalls for 3.5s before deploying his parachute. What was the person's final speed before deploying the parachute? Ignore air resistance.

None of these

Explanation:

A person falling without air resistance only has the force of gravity acting on them. Thus, the acceleration of gravity multiplied by time yields the final speed of . The negative sign just indicates that the person is falling downward.

### Example Question #97 : High School Physics

Usain Bolt accelerates from rest to  over a distance of 100m. What is his acceleration? Assume the acceleration is constant.

Explanation:

We are given final velocity and we know initial velocity is 0. We can use the following kinematics formula to relate final speed, initial speed, acceleration, and displacement:

The red term is zero since Usain starts from rest. Plug in the remaining values and solve for acceleration.

### Example Question #98 : High School Physics

A drone needs to reach  to take off and it takes 600m to reach this speed. What is its acceleration?