Torque & Rotational Motion Basics AP Phys1

The time required for one complete revolution is:

• torque

• frequency

• period

• rotational kinetic energy

If F is force and r is the radius vector, then torque is given by

• r x F

• r.F

• F x r

• none of these

Unit of torque is

• Nm

• J

• N/m

• Watt

Which has more rotational inertia? (consider all objects have equal radius)

• Hollow sphere
• solid sphere
• disk
• cylinder

Which has greater linear speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?

• the inside horse
• the outside horse
• Neither

A small mass is rotating without friction in a circle. The string is shortened by pulling it through the axis of rotation with no external torque. What happens to the tangential velocity?

• It increases
• It decreases
• It stays the same

The velocity of centre of mass of the system remains constant, if the total external force acting on the system is

• minimum

• maximum

• unity

• zero

When a torque acting upon a system is zero. Which of the following will be constant?

• Force

• Linear impulse

• Linear momentum

• Angular momentum

Suppose you are designing an engineless car for a downhill coasting race.  What type of wheels would be the best?

• Solid disks.
• Hoops.
• Hollow cylinders.
• Diamond encrusted triangles.

Stars originate as large bodies of slowly rotating gas.  Because of gravity, these clumps of gas slowly decrease in size.  What happens to the angular speed of the start as it shrinks?

• It rotates faster.
• It rotates slower.
• It starts to accelerate in the forward direction.
• The rotation rate stays the same.