Physics Chapter 7 (Momentum)

A 30-kg girl and a 25-kg boy face each other on friction-free roller blades. The girl pushes the boy, who moves away at a speed of 1.0 m/s. The girl's speed is

30Kg V= 25kg 1 m/s = 25/30=.83

What is the average momentum of a 70-kg runner who covers 400 m in 50s?

70kg*(400m/50s)= 560 Kg m/s

After a firecracker falling through the air explodes, the net momentum of its fragments decreases.

False

If the net external force acting on a system is zero, then the total momentum of the system is zero.

False

Impulses are smaller when bouncing takes place.

False

The momentum change of an object is equal to the

Impulse acting on it

If the momentum of an object changes and its mass remains constant

It's velocity is changing, it's accelerating, and there is a force acting on it

If Superman at rest in free space throws an asteroid that has more mass than Superman, then which moves faster?

Superman

Which has more momentum, a large truck moving at 30 miles per hour or a small truck moving at 30 miles per hour?

The large truck

A Ping-Pong ball launcher is fired. Compared to the force on the ball, the force on the launcher is

The same

If a net force acts on a system, the system's momentum will change.

True

The padding on car dashboards lengthens the time of passenger's impact during a collision

True

The cannonball launched from a cannon with a long barrel will be faster because the cannonball receives a greater

impulse

Skelly the skater traveling at high speed needs a certain amount of force to stop him. More stopping force will be needed if he has

more mass, more momentum, and less stopping distance

Compared to a sports car moving at 30 miles per hour, the same sports car moving at 60 miles per hour has

twice as much momentum