Question

HELP!

Mr. Mock sets up a demonstration on a moving bus. The device consists of a ball attached with a string to a magnet. He uses the magnet to hang the ball from the top of the school bus as the bus turns the corner at a constant speed. What will the ball do?

a
The ball swings backward.

b
The ball swings forward.

c
The ball swings to the outside of the curve.

d
The ball swings toward the inside of the curve

Answer 1

The ball swings to the outside of the curve (assuming that the road is level.)

Step-by-step explanation:

Assume that the air resistance on the ball in this question is negligible. The only forces acting on this ball will be tension that the string exerts on this ball and the weight of the ball.

Since the ball is in a centripetal motion, the net force on this ball will point directly to the center of the curve.

Refer to the diagram attached. The net force on this ball is the vector sum of weight and tension. Since weight points downwards, tension will need to point upwards to balance weight and toward the center of the curve, so that resultant force points horizontally toward the center of the curve.

The tension on the ball points along the string away from the ball (toward the ceiling.) For the tension that the string exerts on this ball to point toward the center of the curve and upwards, the ball will need to swing away from the center of the curve (as show in the diagram.)

Therefore, the ball will swing towards the outside of the curve (away from the center of the curve.)