physics

A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at

1/3 m/s.

How is the impulse -momentum relationship related to Newton's second law?

F=ma=mΔv/Δt, so Ft=Δ(mv)

What does it mean to say that momentum is conserved?

It means momentum does not change.

When you are struck by a moving object, is it favorable that the object makes contact with you over a short time or over a long time?

Long contact time decreases the magnitude of the average force and is favorable.

In which is momentum conserved: an elastic collision or an inelastic collision?

Momentum is conserved in elastic and inelastic collisions.

The impulse-momentum relationship is a direct result of

Newton's 2nd law.

The conservation of momentum is most closely related to

Newton's 3rd law.

Why is it advantageous to roll with the punch in boxing?

Rolling with the punch increases contact time, which decreases the force.

Why is a force that is applied for a short time more effective in karate?

The average force is increased.

Which has a greater momentum: a heavy truck at rest or a moving skateboard?

The moving skateboard.

Is it correct to say that, if no net impulse is exerted on a system, then no change in the momentum of the system will occur?

Yes, always

It is correct to say that impulse is equal to

a corresponding change in momentum

Which has the greater momentum when moving?

either of these depending on speed

A boxer rides with the punch so as to reduce _______.

force

Cassy can get more force on the bricks she breaks with a blow of her bare hand when _______.

her hand is made to bounce from the bricks.

When a boxer moves into an oncoming punch, the force experienced is

increased

An impulse can be increased by

increasing the force or increasing the time interval.

A slowly moving ship can have a greater momentum than a fast-moving racing car when _______.

its mass times velocity is greater than that of the car.

if you can't avoid being hit by a fast-moving object, you'll suffer a smaller contact force if you can extend that force over a

longer time

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will

move in the opposite direction at a lower speed.

The quantity that is called impulse can be measured by the _______.

product of force and time.

Two identical freight cars roll without friction (one at 1 m/s, the other at 2 m/s) toward each other on a level track. They collide, couple together, and roll away in the direction of

the faster car

A lunar vehicle is tested on Earth at a speed of 10 km/h. When it travels as fast on the Moon, is its momentum more, less, or the same?

the same

The force on a dropped apple hitting the ground depends upon

the time of contact with the ground. the speed of the apple just before it hits. whether or not the apple bounces. all of the above

When two vehicles collide, momentum is conserved _______.

whether the collision is elastic or inelastic.