DC -- Impulse

The effect of a force on an object depends on _____

• how long the force acts on the object

• the direction of the force

• the distance the object moved

• the frictional surface

The change in motion of a tennis ball thrown upward is caused by what force?

• kinetic

• gravitational

• potential

• applied

What is an impulse?

• the difference between the force and the speed of the object

• the product of the net force and the momentum

• the product of the net force and the time

• the sum of all forces acting on an object

Why do airbags save lives?

• They reduce the momentum of the car by reversing the net force.

• They provide an equal and opposite net force on the car after a crash.

• They provide a smaller net force on the occupants in a crash.

• They allow the net force on the occupants to act over a much longer time when there is a sudden stop.

Which objects are used in the calculation example problem in the reading?

• billiard balls

• objects launched from a cannon

• crashing cars

• bicycles

Our definition of impulse includes an assumption that the ____ is constant over the time interval Δt.

• velocity

• force

• momentum

• displacement

A skydiver landing with a parachute can reduce the force on his legs by doing what?

• landing with feet apart

• landing at a higher speed

• rolling on the ground after landing

• reducing the mass of the parachute