Question 1

Consider a solid sphere of radius R and mass M rolling without slipping. Which form of kinetic energy is larger, translational or rotational?

Accepted Answer

The answer of Consider a solid sphere of radius R...

Question 2

As you are leaving a building, the door opens outward. If the hinges on the door are on your right, what is the direction of the angular velocity of the door as you open it?

Accepted Answer

The answer of As you are leaving a building, the...

Question 3

FIGURE 10-1 -The rotating systems shown in Fig. 10-1 differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). If you release the hanging blocks simultaneously from rest, and call t_L the time taken by the block on the left and t_R the time taken by the block on the right to reach the bottom, respectively, then

Accepted Answer

The answer of FIGURE 10-1 
-The rotating systems shown in...

Question 4

Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger angular speed?

Accepted Answer

The answer of Two children are riding on a merry-go-round....

Question 5

FIGURE 10-1 
-The rotating systems shown in Fig. 10-1 differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). If you release the hanging blocks simultaneously from rest,

Accepted Answer

The block at right lands first because the masses are closer to the axis of rotation, reducing the moment of inertia and allowing the system to accelerate faster.

Question 6

A dumbbell-shaped object is composed by two equal masses, m, connected by a rod of negligible mass and length r. If I₁ is the moment of inertia of this object with respect to an axis passing through the center of the rod and perpendicular to it and I₂ is the moment of inertia with respect to an axis passing through one of the masses we can say that

Accepted Answer

The answer of A dumbbell-shaped object is composed by two...

Question 7

If a constant net torque is applied to an object, that object will

Accepted Answer

A constant net torque applied to an object results in a constant angular acceleration, according to Newton's second law for rotation.

Question 8

A rigid body is rotating about a fixed axis through the origin. A point on the object located on the x-axis at time t is moving in the positive z direction. What is unit vector in the direction of the angular velocity of the body?

Accepted Answer

The answer of A rigid body is rotating about a...

Question 9

Two equal forces are applied to a door. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force exerts the greater torque?

Accepted Answer

Torque is calculated as the product of force and the distance from the pivot point. Since the force applied at the doorknob is farther from the pivot (hinges) than the force applied at the midpoint, it exerts a greater torque.

Question 10

What is the quantity used to measure an object's resistance to changes in rotational motion?

Accepted Answer

The quantity used to measure an object's resistance to changes in rotational motion is its moment of inertia, which depends on the distribution of mass within the object. Choices A, C, D, and E are related to rotational motion, but they do not directly measure an object's resistance to changes in rotational motion.

Question 11

Consider a hoop of radius R and mass M rolling without slipping. Which form of kinetic energy is larger, translational or rotational?

Accepted Answer

The answer of Consider a hoop of radius R and...

Question 12

A rigid body is rotating about a fixed axis through the origin. The angular velocity is ω  , where ω is positive. What is the unit vector in the direction of the velocity of a point on the body located on the positive y axis?

Accepted Answer

The answer of A rigid body is rotating about a...

Question 13

Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger tangential acceleration?

Accepted Answer

Tangential acceleration is directly proportional to the distance from the axis of rotation. Therefore, the child at the greater distance from the axis of rotation (Child A) will have a larger tangential acceleration than the child closer to the axis (Child B). The centripetal acceleration may be different for each child, but that is not relevant to the question of which has the larger tangential acceleration.

Question 14

Rolling without slipping depends on

Accepted Answer

The answer of Rolling without slipping depends on
...

Question 15

When you ride a bicycle, in what direction is the angular velocity of the wheels?

Accepted Answer

The answer of When you ride a bicycle, in what...

Question 16

Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger centripetal acceleration?

Accepted Answer

Centripetal acceleration is directly proportional to the distance from the axis of rotation. Therefore, Child A will have a larger centripetal acceleration than Child B.

Question 17

Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger tangential speed?

Accepted Answer

The tangential speed of a point on a rotating object is directly proportional to its distance from the axis of rotation. Therefore, child A, who is at a greater distance from the axis of rotation, will have a larger tangential speed than child B.

Question 18

Two equal forces are applied to a door at the doorknob. The first force is applied perpendicular to the door; the second force is applied at 30° to the plane of the door. Which force exerts the greater torque?

Accepted Answer

Torque is maximized when the force is applied perpendicular to the lever arm. The first force is perpendicular, thus exerting greater torque than the second force applied at an angle.

Question 19

A boy and a girl are riding on a merry-go-round that is turning. The boy is twice as far as the girl from the merry-go-round's center. If the boy and girl are of equal mass, which statement is true about the boy's moment of inertia with respect to the axis of rotation?

Accepted Answer

The answer of A boy and a girl are riding...

Question 20

A wheel of radius R is rolling on a horizontal surface. Its center is moving forward with speed v. A point on the wheel a distance r/3 below the center is moving forward at a speed 2v/3. The wheel is

Accepted Answer

If the wheel is rolling without slipping, then the speed of the point on the wheel in contact with the ground must be equal to the speed of the center of the wheel. Since the point on the wheel a distance r/3 below the center is moving forward at a speed of 2v/3, it means that the wheel is rolling without slipping, and the correct answer is A.

Quiz 10: Rotational Motion