Concepts of Physics

What is the relationship between the center of gravity and the support base for an object that is in stable equilibrium? A vertical line through the center of gravity must pass through the center of the support base. The center of gravity must be below the support base. The center of gravity must be in the center of the support base of the object. A vertical line through the center of gravity must pass inside the support base of the object.

A vertical line through the center of gravity must pass inside the support base of the object.

Why doesn't the Leaning Tower of Pisa topple over? A vertical line through the center of gravity passes through the center of its support base. The center of gravity is at the center of the building. A vertical line through the center of gravity passes inside its support base. The center of gravity is suspended below its support base.

A vertical line through the center of gravity passes inside its support base.

What is required to change the angular momentum of a system? Torque Force External torque External force

External torque

If a skater who is spinning pulls her arms in so as to reduce her rotational inertia by half, by how much will her angular momentum change? By how much will her rate of spin change? Her angular momentum is doubled. Her spin rate is doubled. Her angular momentum does not change. Her spin rate doubles. Her angular momentum is cut in half. Her spin rate is cut in half. Her angular momentum is cut in half. Her spin rate does not change.

Her angular momentum does not change. Her spin rate doubles.

Where is the center of mass of a hollow soccer ball? In the center of the ball At the top-dead-center of the ball At the lowest point of the ball Halfway between the center and the lowest point of the ball

In the center of the ball

As distance increases between most of the mass of an object and its center of rotation, how does rotational inertia change? It increases. It goes to zero. It decreases. It stays the same.

It increases.

What is meant by the "lever arm" of a torque? It is the distance between the point at which a force is applied and the center of mass of an object. It is the distance between the point at which a force is applied and the rotational axis. It is the perpendicular distance from the rotational axis to the line along which the force acts. It is the angle between the applied force vector and the rotational axis.

It is the perpendicular distance from the rotational axis to the line along which the force acts.

What are the units of measurement for tangential speed? For rotational speed? Vie w Available Hint(s)RPM for tangential, m/s for rotational m/s for tangential, RPM for rotational RPM for both m/s for both

On a rotating turntable, how do tangential speed and rotational speed vary with distance from the center? Both increase in speed with distance.Both are constant.Rotational speed increases with distance. Tangential speed is constant.Tangential speed increases with distance. Rotational speed is constant.

Inertia depends on mass; rotational inertia depends on mass and something else. What? The distribution of mass about the axis of rotation The angular speed The tangential speed of the rim The distribution of mass along the axis of rotation

The distribution of mass about the axis of rotation

Which is easier to get swinging: a baseball bat held at the narrow end or a bat held closer to the massive end (choked up)? Also answer for a short bat versus a long bat. The easiest is at the narrow end and a short bat. The easiest is choked up and a short bat. The easiest is choked up and a long bat. The easiest is at the narrow end and a long bat.

The easiest is choked up and a short bat.

What does a torque tend to do to an object? Torque tends to increase the linear speed of the object. Torque tends to decrease the rotational inertia of the object. Torque tends to increase the rotational inertia of the object. Torque tends to twist or change the state of rotation of the object.

Torque tends to twist or change the state of rotation of the object

When you whirl a can at the end of a string in a circular path, what is the direction of the force you exert on the can? Toward the center of the circle Radially outward from the center of the circle Tangent to the circle in the direction of motion of the can Tangent to the circle and opposite in direction to the motion of the can

Toward the center of the circle

The tangential speed on the outer edge of a rotating carousel is _______. four times as great for twice the distance less than toward the center greater than toward the center the same as toward the center

greater than toward the center

What are the units of measurement for tangential speed? For rotational speed? RPM for tangential, m/s for rotational m/s for tangential, RPM for rotational RPM for both m/s for both

m/s for tangential, RPM for rotational

When a rock tied to a string is whirled in a horizontal circle, doubling the speed _______. doubles the tension in the string doubles the velocity, but the string tension remains the same decreases the velocity quadruples the tension in the string

quadruples the tension in the string