Chapter 8 Physics Test
A railroad diesel engine coasting at 10km.h runs into a stationary flatcar. The diesel weights 4 times as much as the flatcar. Assuming the cars couple together, how fast are they moving after the collision?
(4)(10km/h)+0=(4+1)vf (40km/h=5vf)/5=8km/h
A 30kg girl and a 25kg boy face each other on friction-free roller skates. The girl pushes the boy, who moves away at a speed of 1.0m/s. what is the girl's speed?
.83m/s
What is the average momentum of a 70-kg runner who covers 400 m in 50s? (P=d*m/t)
560kgm/s
After a firecracker falling through the air explodes, the net momentum of its fragments decreases.
False
If a net force acts on a system, the system's momentum will change
False
If the net external force acting on a system is zero, then the total momentum of the system in zero.
False
The cannonball launched from a cannon with a long barrel will be faster because the cannonball receives a greater...
Impulse
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 impulse on he ball, the amount of impulse on the launcher is...
The same
Impulses are smaller when bouncing takes place
True
The padding on care dashboards lengthens the time of a passenger's impact during a collision
True
Compared to a sports care moving at 30 miles per hour, the same sports care moving at 60 miles per hour has...
Twice as much momentum
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
its velocity is changing it is accelerating (or decelerating) there is a force acting on it.
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 less stopping distance