3.4.1 Forces and Uniform Circular Motion

Question 1

Forces and Uniform Circular Motion

Answer 1

• In uniform circular motion, acceleration, , is always toward the center of the circle.•In uniform circular motion, a large velocity and a small radius imply large force.
• In uniform circular motion, the contact force (normal force) is always toward the center of the circle.
• In a conical pendulum, the velocity that will produce uniform circular motion is

Question 2

The following diagrams show four versions of the path of an object in uniform circular motion. Three vectors are shown: the velocity vector, v; the acceleration vector, a; and the position vector, r. Which diagram correctly identifies these vectors?

Answer 2

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Question 3

The force diagram shows an object being swung by a string in uniform circular motion. The centripetal force, T, is indicated. Which of the following statements is correct?

Answer 3

• A large velocity and a small radius imply a large force.
• As the length of the string decreases, its tension increases.
• A small velocity and a large radius imply a small force.

Question 4

The following diagram shows a steel ball swinging from a pendulum. The ball has been set in motion by hand. The person who swung the ball tried to swing it so that it would follow a flat, circular path. Which of the following statements regarding the resulting motion is correct?

Answer 4

For any given angle of theta, there is only one specific velocity at which the ball can be swung that will result in uniform circular motion

Question 5

The diagram shows a physical diagram and a force diagram of a conical pendulum. The x-axis and y-axis are also shown. The ball is moving in uniform circular motion. Which of the following equations contains the correct equation to solve for forces in the y-direction?

Answer 5

T cos theta - mg = 0

Question 6

The following diagram shows the path of an object in uniform circular motion. Acceleration, velocity and position vectors are indicated. Which of the following equations correctly describes the acceleration of the object?

Answer 6

a = v^2/r

Question 7

The following diagram shows a physical diagram and a force diagram of a conical pendulum. The x-axis and y-axis are also shown. The ball is moving in uniform circular motion. Which of the following equations contains the correct equation to solve for forces in the x-direction?

Answer 7

T sin theta = mv^2/r

Question 8

The following diagram shows a physical diagram and a force diagram of a conical pendulum. The x-axis and y-axis are also shown. The ball is moving in uniform circular motion. Which of the following equations contains the correct equation to solve for velocity, v ?

Answer 8

v = sqrt(gRtan theta)

Question 9

Which of the following statements regarding uniform circular motion is not correct?

Answer 9

In uniform circular motion, the contact force (normal force) is always opposite the center of the circle.

Question 10

Which of the following statements correctly describes the physical laws of uniform circular motion?

Answer 10

• In uniform circular motion, objects accelerate toward the center of the circle, so there must be a centripetal force.
• The contact force, or F normal, on an object in uniform circular motion is always toward the center of the circle