Question 1

A mechanic uses a wrench of length $$L = 0.5\ \mathrm{m} to $$loosen a bolt. If he applies a force of $$F = 40\ \mathrm{N} at an $$angle of $$60^\circ to $$the wrench, what is the magnitude of the torque produced about the bolt?

Accepted Answer

$$	au = 17.3\ \mathrm{Nm}$$

Question 2

Which of the following statements about torque is correct?

Accepted Answer

A torque that tends to rotate an object counterclockwise is considered positive.

Question 3

A force of $$F = 30\ \mathrm{N} is $$applied perpendicular to a door at a distance $$d = 0.8\ \mathrm{m}$$ from the hinge. What is the torque about the hinge?

Accepted Answer

$$	au = 24\ \mathrm{Nm}$$

Question 4

A student pushes on a wrench with a force of $$25\ \mathrm{N} at an $$angle of $$0^\circ$$ relative to the wrench (along its length). The wrench is $$0.4\ \mathrm{m}$$ long. What is the torque about the bolt?

Accepted Answer

$$	au = 0\ \mathrm{Nm}$$

Question 5

Which of the following does NOT affect the magnitude of the torque produced by a force?

Accepted Answer

The angular velocity of the object

Question 6

A force $$F is $$applied at a distance $$L$$ from a pivot at an angle $$	heta to $$the lever arm. Which equation correctly gives the torque $$	au$$?

Accepted Answer

$$	au = FL\sin	heta$$

Question 7

A seesaw is balanced at its center. If a child sits $$2\ \mathrm{m}$$ from the pivot and applies a downward force of $$150\ \mathrm{N}$$, what is the torque about the pivot?

Accepted Answer

$$	au = 300\ \mathrm{Nm}$$

Question 8

A force of $$10\ \mathrm{N} is $$applied at the end of a $$0.5\ \mathrm{m}$$ long rod at an angle of $$90^\circ to $$the rod. What is the torque about the pivot?

Accepted Answer

$$	au = 5\ \mathrm{Nm}$$

Question 9

If two equal forces are applied at equal distances from a pivot, but one is perpendicular to the lever arm and the other is at $$45^\circ$$, which produces the greater torque?

Accepted Answer

The force perpendicular to the lever arm

Question 10

A net torque is applied to a stationary wheel. What happens to the wheel?

Accepted Answer

Its angular velocity increases

Question 11

A force of $$F = 50\ \mathrm{N} is $$applied at a distance $$d = 0.3\ \mathrm{m}$$ from the axis of rotation at an angle of $$30^\circ to $$the lever arm. What is the torque produced?

Accepted Answer

$$	au = 12.5\ \mathrm{Nm}$$

Question 12

Which of the following best describes the lever arm in the context of torque?

Accepted Answer

The perpendicular distance from the axis of rotation to the line of action of the force

Question 13

A person pushes on a door at a point $$0.9\ \mathrm{m}$$ from the hinge with a force of $$25\ \mathrm{N} at an $$angle of $$60^\circ to $$the door. What is the torque about the hinge?

Accepted Answer

$$	au = 19.5\ \mathrm{Nm}$$

Question 14

Which of the following is true about the net torque acting on an object?

Accepted Answer

It is the sum of all the torques acting on the object.

Question 15

A force of $$F = 15\ \mathrm{N} is $$applied at the end of a $$0.6\ \mathrm{m}$$ long rod at an angle of $$0^\circ to $$the rod. What is the torque about the pivot?

Accepted Answer

$$	au = 0\ \mathrm{Nm}$$

Question 16

A wrench is used to loosen a bolt. Which of the following actions will NOT increase the torque applied to the bolt?

Accepted Answer

Applying the force at a smaller angle to the lever arm

Question 17

A force of $$F = 12\ \mathrm{N} is $$applied at a distance $$d = 0.5\ \mathrm{m}$$ from the axis at an angle of $$90^\circ. $$What is the torque?

Accepted Answer

$$	au = 6\ \mathrm{Nm}$$

Question 18

Which of the following best explains why a door is easier to open when you push at the edge farthest from the hinge?

Accepted Answer

The lever arm is longer, increasing the torque for the same force.

Question 19

A force of $$F = 25\ \mathrm{N} is $$applied at the end of a $$1.2\ \mathrm{m}$$ long rod at an angle of $$30^\circ to $$the rod. What is the torque about the pivot?

Accepted Answer

$$	au = 15\ \mathrm{Nm}$$

Chapter 10.4: Torque – Rotational Motion Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards