Chapter 3, Problem 17Q

Solution

Part a

To Determine: The place where the ball land if it is enclosed in a train car moving at constant velocity.

Solution:The ball lands at the same position.

Explanation:

When the ball is thrown upwards, it is imparted vertical velocity. There is also horizontal component of the velocity due to inertia of motion which is constant because the train car moves horizontally at constant velocity.

The vertical velocity slows down and becomes zero at highest point and the ball falls back to the same point in her reference point.

Part b

To Determine: The place where the ball lands if it is enclosed in a train car which accelerates.

Solution:The ball will land behind the initial position.

Explanation:

When the ball is thrown upwards, it is imparted vertical velocity. There is also horizontal component of the velocity due to inertia of motion because the train car moves horizontally.

The vertical velocity slows down and becomes zero at highest point and then the ball falls back but as the train car is accelerating, the ball will fall behind the starting position in her reference frame because the person moves forward with the train.

Part c

To Determine: The place where the ball lands if it is enclosed in a train car which decelerates.

Solution:The ball will land ahead of the initial position.

Explanation:

When the ball is thrown upwards, it is imparted vertical velocity. There is also horizontal component of the velocity due to inertia of motion because the train car moves horizontally.

The vertical velocity slows down and becomes zero at highest point and then the ball falls back but as the train car is decelerating, the ball will fall ahead of the starting position in her reference frame because the person is also slowing down along with the train.

Part d

To Determine: The place where the ball land if it is enclosed in a train car which rounds a curve.

Solution:The ball will land at the side of the initial position towards the centre of the curved path.

Explanation:

When the ball is thrown upwards, it is imparted vertical velocity. There is also horizontal component of the velocity due to inertia of motion because the train car is moving horizontally.

The vertical velocity slows down and becomes zero at highest point and then the ball falls back but as the train car is moving in a curved path, the ball will fall at the side of the starting position towards the centre of the curved path in her reference frame.

Part e

To Determine: The place where the ball land if the train car moves at constant velocity and is open to the air.

Solution:The ball will land behind the initial position.

Explanation:

When the ball is thrown upwards, it is imparted vertical velocity. There is also horizontal component of the velocity due to inertia of motion because the train car is moving horizontally.

The vertical velocity slows down and becomes zero at highest point, and then the ball falls back but as the train car is open to air, there is also air resistance acting which causes a lag. The person moves forward with the train but the ball falls behind the initial position.