Physics Worksheet: Angular Momentum and Torque

In stable equilibrium, what happens when the system is rotated?

• Center of gravity is lowered

• No change in energy

• System remains in motion

• Center of gravity is raised

Answer explanation

In stable equilibrium, when the system is rotated, the center of gravity is raised. This occurs because the system moves to a higher potential energy state, indicating that it is less stable in that position.

What is neutral equilibrium?

• Mass is uniformly distributed

• Center of gravity stays the same when rotated

• Center of gravity is raised

• System is unbalanced

Answer explanation

Neutral equilibrium occurs when the center of gravity remains unchanged during rotation, meaning the system is stable in any position. This is why the correct answer is 'Center of gravity stays the same when rotated'.

For vertical stability, where must the center of gravity be?

• Next to the pivot

• At the midpoint of the object

• Below the base

• Above the base of support

Answer explanation

For vertical stability, the center of gravity must be above the base of support. This positioning ensures that the object remains balanced and does not tip over, as the gravitational force acts downward through the center of gravity.

Where does the center of gravity hang in a suspended system?

• To the side of the support

• At the top of the object

• Above the base

• Directly below the support

Answer explanation

In a suspended system, the center of gravity hangs directly below the support. This position ensures stability, as the weight is balanced directly beneath the point of suspension.

What is the formula for angular momentum?

• L = m v

• L = I omega

• L = F r

• L = tau t

Answer explanation

The correct formula for angular momentum is L = I omega, where I is the moment of inertia and omega is the angular velocity. This formula describes how rotational motion is quantified, unlike the other options.

Omega represents (a)   in angular motion.

• Rotational force
• Angular velocity

Answer explanation

In angular motion, omega (ω) represents angular velocity, which is the rate of change of angular displacement over time. It indicates how fast an object rotates around an axis, making 'Angular velocity' the correct choice.

What is always conserved in the absence of external torque?

• Force

• Angular momentum

• Center of gravity

• Linear acceleration

Answer explanation

In the absence of external torque, angular momentum remains constant due to the conservation laws of physics. This means that the total angular momentum of a system does not change, making it the correct answer.

What happens to angular velocity if moment of inertia decreases?

• Torque increases

• Angular velocity decreases

• System becomes unstable

• Angular velocity increases

Answer explanation

According to the conservation of angular momentum, if the moment of inertia decreases while no external torque is applied, the angular velocity must increase to keep the product of moment of inertia and angular velocity constant.

What happens to a spinning skater when they pull in their arms?

• They slow down

• They spin faster due to reduced moment of inertia

• They become unstable

• Their torque increases

Answer explanation

When a skater pulls in their arms, they reduce their moment of inertia. According to the conservation of angular momentum, this causes them to spin faster, making the correct answer "They spin faster due to reduced moment of inertia."

Match the following units with their corresponding physical quantities.

• Speed

• kg*m/s

• Momentum

• N*m

• Torque

• m/s

• Energy

• Joules

Answer explanation

Torque is measured in Newton-meters (N*m), which represents the force applied at a distance. The other options do not represent torque units, making N*m the correct choice.