Question 1

In the context of uniform circular motion, which of the following statements best describes the direction of the acceleration vector at any point on the path?

Accepted Answer

It points radially inward toward the center of the circle.

Question 2

A car is making a sharp right turn. From the perspective of an observer inside the car (a non-inertial frame), what 'force' do they feel, and in which direction?

Accepted Answer

A centrifugal force to the left, away from the center of the turn.

Question 3

Which of the following equations correctly gives the centripetal acceleration $$a_c$$ for an object moving at constant speed $$v_T in a $$circle of radius $$r$$?

Accepted Answer

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

Question 4

A 2 kg object moves in a horizontal circle of radius 3 m at a constant speed of 6 m/s. What is the magnitude of the centripetal force acting on the object?

Accepted Answer

$$F_c = 24\ \mathrm{N}$$

Question 5

Which of the following best describes 'apparent weight' as experienced in an accelerating elevator?

Accepted Answer

It is the normal force exerted by the floor, which can differ from your actual weight depending on the elevator's acceleration.

Question 6

A person stands on a scale in an elevator that is accelerating upward at $$2\ \mathrm{m/s^2$}. If $$the person's mass is $$70\ \mathrm{kg}$$, what does the scale read?

Accepted Answer

$$826\ \mathrm{N}$$

Question 7

Which of the following is NOT a characteristic of an inertial frame of reference?

Accepted Answer

Observers feel fictitious forces such as centrifugal force.

Question 8

During a 'weightless' parabolic flight, such as the one performed by the band OK GO, what is the relative acceleration of objects inside the plane?

Accepted Answer

It is zero.

Question 9

Which of the following best explains why you feel 'weightless' when in free fall?

Accepted Answer

The normal force acting on you is zero.

Question 10

A 0.5 kg mass is swung in a vertical circle of radius 1.2 m at a speed of 4 m/s. What is the centripetal force at the bottom of the circle?

Accepted Answer

$$F_c = 6.67\ \mathrm{N}$$

Question 11

Which of the following forces can provide the centripetal force for an object moving in a horizontal circle?

Accepted Answer

Any force that points toward the center, such as tension, friction, or the normal force

Question 12

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

Accepted Answer

It is halved.

Question 13

Which of the following statements about pendulums is correct according to the study materials?

Accepted Answer

Centripetal force changes the direction of the pendulum's motion, while the restoring force changes its speed.

Question 14

A digital scale measures which of the following quantities when you stand on it in an elevator?

Accepted Answer

The normal force exerted by the scale on you

Question 15

In a non-inertial frame of reference, such as a rotating amusement park ride, which of the following is true about the forces experienced by a rider?

Accepted Answer

The rider feels a fictitious centrifugal force pushing them outward, which is the result of inertia.

Question 16

If a car travels around a curve of radius $$r at a $$constant speed $$v$$, what happens to the required centripetal force if the speed is doubled?

Accepted Answer

It is quadrupled.

Question 17

Which of the following best describes the process of finding the change in velocity ($$\Delta \vec{v}) $$between two points in circular motion, as shown in the provided images?

Accepted Answer

By subtracting the initial velocity vector from the final velocity vector: $$\Delta \vec{v} = \vec{v}_f - \vec{v}_i$$

Question 18

A 1.5 kg object moves in a circle of radius 2 m at a speed of 3 m/s. What is the magnitude of the centripetal acceleration?

Accepted Answer

$$a_c = 4.5\ \mathrm{m/s^2$}$$

Question 19

Which of the following is a correct statement about weightlessness in orbit?

Accepted Answer

Astronauts are in free fall, experiencing no normal force from a surface.

Uniform Circular Motion, Frames of Reference, and Apparent Weight

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