ROTATIONAL MOTION

What is the physical meaning of the equation τ = dl/dt for a single particle?

• It describes thermal energy
• It relates to gravitational potential
• It measures electric charge
• Torque causes changes in rotational motion just as force causes changes in linear motion

In the derivation of τ = dl/dt, why is dr/dt × p equal to zero?

• Because p is zero
• Because r is constant
• Because time derivative of r is undefined
• Because dr/dt and p are parallel vectors

What is the relationship between the direction of torque and the change in angular momentum?

• They are always opposite
• Torque has no directional effect
• Change in L is random
• Torque determines the direction of the change in angular momentum

How does the right-hand rule help in determining angular momentum direction?

• It measures torque magnitude
• It calculates linear speed
• It finds center of mass
• It gives the direction perpendicular to the plane of rotation based on spin direction

What would happen if the bicycle rim were not spinning when one string is released?

• It would float in place
• It would start spinning automatically
• It would rise upward
• It would tilt or fall due to unbalanced torque