Chapter 7, Problem 13Q

(a)

To determine

The direction of the change in momentum of the ball.

Answer to Problem 13Q

Direction of the vertical component of momentum will remain unchanged that is in the downward direction. Direction of the horizontal component will be reverse that isit will have a negative x -component.

Explanation of Solution

Introduction:

According to the law of conservation of momentum, momentum before and after the collision must remain equal.

A ball is coming from the upward direction making an angle of $45°$ with the wall as shown below.

  

Thus, the ball will make two components, one in vertical and another in the horizontal direction. Now, because the ball is moving in the downward direction, vertical component will remain unchanged as shown in the figure.

Perhaps, incase of horizontal direction, as the wall is on the right side of the incoming ball. Thus, wall will not move back. But, will exert an opposite force on the ball to fall back making the same inclination. Thus, the ball will move in the left direction. So, direction of the horizontal component momentum will be reverse that isit will have a negative x -component.

(b)

To determine

The direction of the force on the wall.

Answer to Problem 13Q

Direction on the force of the wall will be inpositive x -direction.

Explanation of Solution

Introduction:

According to the law of conservation of momentum, momentum before and after the collision must remain equal.

A ball is coming from the upward direction making an angle of $45°$ with the wall as shown below.

  

Since the ball is colliding with the wall making an angle of $45°$ to the wall. As the wall is rigid. It won’t move but will make the ball fall back in the opposite direction it came from. Thus, ball will exert force on the right side of the wall.

Conclusion:

In the right direction (positive x -direction), force will be applied to the wall.