Q: A 2 kg object moves at 4 m/s in a circle of radius 3 m. What is the magnitude of the net force acting on the object?

$$F = \frac{2 \times 4^2$}{3} = \frac{32}{3} \approx 10.7\ \mathrm{N}$$

Question 1

A bowling ball is rolled smoothly over a frictionless floor and attached to a string, causing it to move in a circle at constant speed. According to the force diagram, what is the direction of the net force acting on the ball?

Accepted Answer

Directly toward the center of the circle

Question 2

Which of the following best explains why the net force on an object moving in a circle at constant speed points toward the center of the circle?

Accepted Answer

Because the object's velocity is always changing direction, requiring a centripetal acceleration

Question 3

A marble is rolled inside a circular ring at constant speed. What happens to the direction of the net force acting on the marble while it is inside the ring?

Accepted Answer

It points directly toward the center of the circle

Question 4

Which equation correctly represents the magnitude of the net force required to keep an object of mass $$m$$ moving at constant speed $$v in a $$circle of radius $$r$$?

Accepted Answer

$$F = \frac{m v^2$}{r}$$

Question 5

In the experiment where a bag is swung in a horizontal circle, what force provides the necessary centripetal force?

Accepted Answer

The tension in the handle

Question 6

If the string holding a ball in circular motion breaks, what path will the ball follow immediately after the break?

Accepted Answer

It will move in a straight line tangent to the circle at the point of release

Question 7

A car travels around a flat circular track at constant speed. What force is responsible for providing the centripetal force?

Accepted Answer

The frictional force between the tires and the road

Question 8

Which of the following statements is true for an object moving in a circle at constant speed?

Accepted Answer

The acceleration is directed toward the center of the circle

Question 9

A 2 kg object moves at 4 m/s in a circle of radius 3 m. What is the magnitude of the net force acting on the object?

Accepted Answer

$$F = \frac{2 	imes 4^2$}{3} = \frac{32}{3} \approx 10.7\ \mathrm{N}$$

Question 10

In the testing experiment, when a marble leaves the circular ring, what is observed about its motion?

Accepted Answer

It moves in a straight line tangent to the point where it left the ring

Question 11

Which of the following best describes the pattern observed in all the experiments regarding the sum of the forces on an object in circular motion?

Accepted Answer

The sum of the forces always points directly toward the center of the circle

Question 12

A satellite orbits Earth in a circular path at constant speed. What provides the centripetal force in this scenario?

Accepted Answer

The gravitational attraction between Earth and the satellite

Question 13

If the radius of the circle is doubled while keeping the speed constant, what happens to the required centripetal force?

Accepted Answer

It is halved

Question 14

Which of the following is the correct expression for the centripetal acceleration $$a_c of an $$object moving at speed $$v in a $$circle of radius $$r$$?

Accepted Answer

$$a_c = \frac{v^2$}{r}$$

Question 15

A child swings a bucket of water in a vertical circle. At the top of the circle, what must be true for the water to stay in the bucket?

Accepted Answer

The speed must be high enough so that the centripetal force is at least equal to the gravitational force

Qualitative Dynamics of Circular Motion: Centripetal Forces

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