Physics 7LC Homework 8

- zero

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. At the instant the hand has stopped pushing, the angular acceleration of the ruler is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page

- not zero and directed into the page

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. At the instant the hand has stopped pushing, the angular velocity of the ruler is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page

- not zero and directed along the ruler

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. At the instant the hand has stopped pushing, the centripetal acceleration of the ruler is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page

- zero

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. At the instant the hand has stopped pushing, the tangential acceleration of the ruler is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page

- not zero and directed out of the page - in the direction opposite angular velocity

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. Imagine next that as the ruler is rotating due to the situation above, the hand applies a force that decreases the ruler's angular velocity (but does not change the direction of angular velocity). The angular acceleration due to this force is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page - in the same direction as angular velocity - in the direction opposite angular velocity

- not zero and directed into the page

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. While the hand is pushing, but before the ruler begins to move, the angular acceleration of the ruler is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page

- zero

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. While the hand is pushing, but before the ruler begins to move, the centripetal acceleration of the ruler is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page

- not zero and directed perpendicular to the ruler but in the plane of the page

A ruler is initially at rest when a student briefly exerts a downward force on the right end, as shown. The magnitude of the force exerted by the student is less than the weight of the ruler. Assume that the pivot point is frictionless. While the hand is pushing, but before the ruler begins to move, the tangential acceleration of the ruler is - zero - not zero and directed into the page - not zero and directed out of the page - not zero and directed along the ruler - not zero and directed perpendicular to the ruler but in the plane of the page

0.0004

Consider a solid ball (sphere) of uniform density. Its radius is 10 cm and mass is 0.1 kg. What is the ball's moment of inertia if it is rotating about its center? Enter in a numerical answer. Assume the SI base units of moment of inertia (but do not enter the units and do not use scientific notation).

- increases by a factor of four

Consider a solid ball (sphere) of uniform density. Its radius is 10 cm and mass is 0.1 kg. What is the ball's moment of inertia if it is rotating about its center? Enter in a numerical answer. Assume the SI base units of moment of inertia (but do not enter the units and do not use scientific notation). Consider the ball in the previous question. Now the ball's radius is doubled compared to the original question, but its mass stays the same as in the original question. The ball's density is uniform (but different than the original ball). The axis of rotation is the same as in the original question. What happens to the moment of inertia? - stays the same - decreases by a factor of two - increases by a factor of two - decreases by a factor of four - increases by a factor of four

- the same as the direction of the torque in case C.

Four identical bars are free to rotate at their centers. A force of the same magnitude is applied to each bar, but in different locations and/or in different directions. The direction of the torque in case B is - the same as the direction of the torque in case C. - different than the direction of the torque in case C.

- greater than the magnitude of the torque in case C.

Four identical bars are free to rotate at their centers. A force of the same magnitude is applied to each bar, but in different locations and/or in different directions. The magnitude of the torque in case B is - greater than the magnitude of the torque in case C. - less than the magnitude of the torque in case C. - equal to the magnitude of the torque in case C.

- not zero because this force is applied in such a way that it could case angular acceleration

Four identical bars are free to rotate at their centers. A force of the same magnitude is applied to each bar, but in different locations and/or in different directions. The torque about the center in case B is - zero because there is no component of force perpendicular to the radius - zero because the radius is zero for this force and axis of rotation - zero because this force is applied in such a way that it could cause angular acceleration - not zero because there is no component of force perpendicular to the radius - not zero because the radius is zero for this force and axis of rotation - not zero because this force is applied in such a way that it could case angular acceleration

- not zero because this force is applied in such a way that it could case angular acceleration

Four identical bars are free to rotate at their centers. A force of the same magnitude is applied to each bar, but in different locations and/or in different directions. The torque about the center in case C is - zero because there is no component of force perpendicular to the radius - zero because the radius is zero for this force and axis of rotation - zero because this force is applied in such a way that it could cause angular acceleration - not zero because there is no component of force perpendicular to the radius - not zero because the radius is zero for this force and axis of rotation - not zero because this force is applied in such a way that it could case angular acceleration

- zero because there is no component of force perpendicular to the radius

Four identical bars are free to rotate at their centers. A force of the same magnitude is applied to each bar, but in different locations and/or in different directions. The torque about the center in case D is - zero because there is no component of force perpendicular to the radius - zero because the radius is zero for this force and axis of rotation - zero because this force is applied in such a way that it could cause angular acceleration - not zero because there is no component of force perpendicular to the radius - not zero because the radius is zero for this force and axis of rotation - not zero because this force is applied in such a way that it could case angular acceleration

- zero because the radius is zero for this force and axis of rotation

Four identical bars are free to rotate at their centers. A force of the same magnitude is applied to each bar, but in different locations and/or in different directions. the torque about the center in case A is - zero because there is no component of force perpendicular to the radius - zero because the radius is zero for this force and axis of rotation - zero because this force is applied in such a way that it could cause angular acceleration - not zero because there is no component of force perpendicular to the radius - not zero because the radius is zero for this force and axis of rotation - not zero because this force is applied in such a way that it could case angular acceleration

- m (meters)

The base SI units of center of mass are: - m (meters) - m^2 - kg m - kg m^2 - kg m/s - unitless

- kg m^2

The base SI units of moment of inertia are: - m (meters) - m^2 - kg m - kg m^2 - kg m/s - unitless

- does not

The center of mass ________ depend on the axis of rotation which is chosen - does - does not

- a location which may or may not be located on the object.

The center of mass of an object is - a location on the object. - a location which may or may not be located on the object. - not a location, but a measure of how hard it is to rotate an object.

- the same as

The center of mass of the rod rotated about its center (case B) is _____ the center of mass of the rod rotated about its end (case A). - the same as - not the same as

- does

The moment of inertia ________ depend on the axis of rotation which is chosen. - does - does not

- not a location, but a measure of how hard it is to rotate an object.

The moment of inertia of an object is - a location on the object. - a location which may or may not be located on the object. - not a location, but a measure of how hard it is to rotate an object.

- greater than

The moment of inertia of the rod rotated about its end (case A) is _____ the moment of inertia of the rod rotated about its center (case B). - greater than - less than - equal to