Review for Physics QZ 9.1-9.2

_______ is the product of the average force on an object and the time intervale over which it acts.

• Angular momentum

• Impulse

• Impulse momentum

• Momentum

An object's _______ is equal to the product of the object's moment of inertia and the objects's angular velocity.

• angular momentum

• inertia

• impulse

• momentum

• angular momentum

• angular impulse-angular momentum theorem

• impulse theorem

• impulse-momentum theorem

How does an air bag save lives?

• It reduces the surface area that a person's body strikes.

• It reduces the force by increasing the time interval during which it acts.

• It exerts the force over a smaller area of the person's body.

An isolated system has a net external force of _______.

• 0 N

• 1 N

• 2 N

• 3 N

A system which does not gain or lose mass is said to be a(n) _______ system.

• angular

• closed

• isolated

• parallel

All forces within an isolated system are _______.

• angular

• due to gravity

• external

• internal

If C is 1 kg and D is 100 kg, and the initial velocities of both balls are 5 m/s, how would the magnitude of the forces exerted by each ball on the other during the collision compare?

• The magnitude of the force of D on C would be greater than of C on D.

• The magnitude of the force of C on D would be greater than of D on C.

• They do not exert forces on each other.

• The magnitude of the forces would be equal.

The law of conservation of momentum states that _______.

• momentum can be created, but it cannot be destroyed

• the momentum of any closed system does not change

• the momentum of any system does not change

• the momentum of any closed system with no net external force does not change

Two skaters, Evelyn and Lily, face each other on near frictionless ice. Evelyn has a mass of 57.4 kg, and Lily has a mass of 48.3 kg. Both are motionless until they push away with a force of 33 N. Then Evelyn has a velocity of 1.4 m/s. What is Lily's velocity?

• -1.7 m/s

• -2.0 m/s

• -2.4 m/s

• -2.8 m/s