### All AP Physics 1 Resources

## Example Questions

### Example Question #51 : Motion In Two Dimensions

Deep in space Object has mass and is initially traveling with velocity . At , it collides with Object , which has mass and is initially motionless. The two objects stick together.

Assuming the collision took place at the origin, determine the location at , fifty five seconds after the collision.

**Possible Answers:**

None of these

**Correct answer:**

Using

Plugging in values:

The momentum will be the same in the final state, so again using

Solving for velocity:

Plugging in values (the total mass is equal to the combined masses:

Using

Plugging in values

### Example Question #51 : Motion In Two Dimensions

Deep in space Object has mass and is initially traveling with velocity . At , it collides with Object , which has mass and is initially motionless. The two objects stick together.

Assuming the collision took place at the origin, determine the location of object at , fifteen seconds before the collision.

**Possible Answers:**

None of these

**Correct answer:**

Using

Plugging in values

### Example Question #52 : Motion In Two Dimensions

A ball rolls off of a high cliff at a constant velocity of . Neglecting air friction, what is the acceleration of the ball in the vertical and horizontal direction just before it hits the ground?

**Possible Answers:**

Vertical:

Horizontal:

Vertical:

Horizontal:

Vertical:

Horizontal:

Vertical:

Horizontal:

**Correct answer:**

Vertical:

Horizontal:

The acceleration due to gravity only affects the object in the vertical direction, which is always . Because there is no external force acting on the ball in the horizontal direction there is no acceleration.

### Example Question #53 : Motion In Two Dimensions

During time period , a rocket ship deep in space of mass travels from to . During time period , the rocket fires. During time period , the rocket travels from to .

Time periods , , and took each.

Determine the momentum during time period .

**Possible Answers:**

None of these

**Correct answer:**

Combining equations:

Plugging in values:

### Example Question #51 : Motion In Two Dimensions

During time period , a rocket ship deep in space of mass travels from to . During time period , the rocket fires. During time period , the rocket travels from to .

Time periods , , and all took

Determine the momentum during time period .

**Possible Answers:**

None of these

**Correct answer:**

Combining equations:

Converting to and plugging in values:

### Example Question #54 : Motion In Two Dimensions

Suppose that a person has walked north and east. What is this person's net displacement from where he initially started?

**Possible Answers:**

**Correct answer:**

To answer this question, it's helpful if we draw the path this person takes.

Now, it's important to realize the difference between distance and displacement. The *distance* this person has traveled is the total amount of walking he has done. So in this case, the distance traveled would be:

However, this is not the answer to our question. The question is asking for the *displacement*, which is the net change in position of this person. We can draw it as follows:

Notice that in the above drawing, we have a right triangle. This will actually simplify things a bit, because we can use trigonometry to find the angle of displacement (shown above in blue). Then, we can use that information to find the displacement (shown above in green).

To find the angle of displacement, we can use the following expression:

Now that we have the angle, we can calculate the displacement using further trigonometry.

An alternative way to solve this problem, and arguably much easier, is to just use the Pythagorean theorem since we have a right triangle.

### Example Question #57 : Motion In Two Dimensions

A quarterback throws a football a horizontal distance of to a wide receiver. The ball was airborne for . The ball had an initial speed of . The ball has a mass of .

Determine the angle between the initial velocity of the football and the ground.

**Possible Answers:**

None of these

**Correct answer:**

Using:

Converting to

Converting yards to meters

Combining equations

Plugging in values:

### Example Question #55 : Motion In Two Dimensions

A quarterback throws a football a horizontal distance of to a wide receiver. The ball was airborne for . The ball had an initial speed of . The ball has a mass of .

Determine the initial vector velocity of the football.

**Possible Answers:**

None of these

**Correct answer:**

Determining horizontal component of velocity:

Using

Solving for

Combining equations

Converting to

Converting yards to meters

Plugging in values:

### Example Question #53 : Motion In Two Dimensions

A quarterback throws a football a horizontal distance of to a wide receiver. The ball was airborne for . The ball had an initial speed of . The ball has a mass of .

Determine the speed at the apex of the throw.

**Possible Answers:**

None of these

**Correct answer:**

At the apex, the only velocity will be in the direction as the ball is at it's maximum height.

Using:

Solving for velocity

Converting yards to meters

Plugging in values

### Example Question #152 : Linear Motion And Momentum

Determine the speed of the football 4 seconds after the throw.

**Possible Answers:**

None of these

**Correct answer:**

Determining horizontal component of velocity:

Using

Solving for

Combining equations

Converting to

Converting yards to meters

Plugging in values:

Using