Rotational Equilibrium & Dynamics

How is torque calculated using the moment arm?

• τ=Fr
• τ=F/r
• τ=r/F
• τ=F + r

a thin 1 m long rod has a 200 g object attached to the left end and a 300 g object attached to the right end.  If the pivot point is in the middle of the rod, the object...

• will be in static rotational equilibrium
• will have a positive angular position
• will have a negative angular position
• is balanced

The diagram shows a wheel (with a radius of 0.10 m) that rotates around an axle (with a radius of 0.02 m).  What force produces the torque with the largest magnitude? (τ=rF)

• A
• B
• C
• D

The diagram shows a wheel (with a radius of 0.10 m) that rotates around an axle (with a radius of 0.02 m).  What is the net torque on the system? (τ=rF)

• 1 Nm, clockwise
• 1 Nm, counterclockwise
• 2 Nm, clockwise
• 3 Nm, counterclockwise

Torque can be described as

• how effectively a force causes a rotation

• the ratio of mass to angular acceleration

• the ratio of moment of inertial to angular acceleration

• None of the other answers

The lever arm is the ________ distance from the axis of rotation to the point where the force is exerted.

• angular

• displaced

• perpendicular

• none of these

Suppose a doorknob is placed at the center of a door. Compared with a door whose knob is located at the edge, what amount of force must be applied to this door to produce the torque needed to open it?

• 1/4 as much

• 1/2 as much

• Twice as much

• Four times as much

Below are the example of rigid body except:

• Beam

• Slab

• Cement

• Column

All the forces rotating counterclockwise will have a _______ torque

• positive

• negative

All the forces rotating clockwise will have a _______ torque

• positive

• negative