Module 9 review questions Flashcards
An object’s velocity vector points 45 degrees northeast. what is the direction of its momentum vector?
The face in the same direction, so it will also be 45 degrees northeast.
Which of the following are legitimate units for momentum?
kgxm/sec^2 ; gxkm/min ; ftxslug/hr ; gxm/sec^2 ;
gxkm/min and ftxslug/hr. Momentum units must have mass times distance divided by time.
Under what conditions can a compact car have the same momentum as a larger, heavier car?
If the small car was traveling with a larger velocity.
A golf ball and a lump of soft clay are both thrown at a wall. They each have the same mass and are thrown at the same velocity, and they each stop dead when they hit the wall. On which object does the wall exert the most impulse?
The wall exerts the same impulse on both. impulse is equal to the change in momentum. They have the same mass and velocity and they both come to a halt.
In the situation from question 4, on which object does the wall exert the most force?
The golf ball because it does not flex like the clay, the all has less time to stop it.
A cat and a mouse are both running with equal kinetic energy. Do they necessarily have the same momentum? Why or why not?
Not necessarily.
Under what conditions is Momentum conserved?
When the sum of the forces acting on the system is zero.
A marksman fires two guns. They each have approximately the same mass and fire their bullets at roughly the same initial velocities. The first fires heavy bullets, while the second fires lighter ones. Which gun has the greater recoil velocity.
the first gun. Since it fires heavier bullets, the momentum will be greater and so will the recoil.
Explain in your own words how a rocket is launched.
A rocket is launched because, as its fuel burns, the combustion products of that fuel speed out under the rocket. These combustion products have momentum. In order to conserve momentum, the rocket must travel in the opposite direction.
Under what conditions in angular momentum conserved?
When the sum of the torques acting on a system is zero.
