Physical science Ch 3
A diver who weighs 500 N steps off a diving board 10 m above the water hits the water with kinetic energy of
5000 J.
A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car?
6 m/s
A shopping cart moves with a kinetic energy of 40 J. If it moves at twice the speed, its kinetic energy is
160 J.
A music console is pushed a distance of 2 m with a force of 20 N. The work done on the console is
40 J.
A 2-kg mass weighs 20 N and is held 4 m above the ground. Its potential energy relative to the ground is
80 J.
It is correct to say that impulse is equal to
change in momentum
If a rhinoceros has momentum, it must also have
kinetic energy.
An object may have potential energy because of its
location
A dog and a mouse run along a road with the same kinetic energy. The faster runner is the
mouse
If you push for an hour against a stationary wall, you do no work
on the wall.
An object lifted 10 m gains a certain amount of potential energy. If it is lifted 20 m, its gain in potential energy is
twice as much.
When you are in the way of a fast-moving object and can't get escape, you will suffer asmaller force if the collision time is
long
A 50-kg sack is lifted 2 m in the same time as a 25-kg sack is lifted 4 m. The power expended in raising the 50-kg sack compared to the power used to lift the 25-kg sack is
the same.
Two billiard balls having the same mass roll toward each other at the same speed. What is the net momentum of the two-ball system?
0 kg∙m/s
Two identical freight cars roll without friction towards each other on a level track. One car rolls at 2 m/s and the other car rolls at 1 m/s. After the cars collide, they couple and roll together with a speed of
0.5 m/s.
If you exert 100 J in 50 s and your power output is
2 W.
A 1000-kg car moving at 10 m/s that brakes to a stop in 5 s has an average braking forceof
2000 N
A 4-kg ball has a momentum of 12 kg∙m/s. What is the ball's speed?
3 m/s
A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is
5/6 m/s.
A freight train rolls along a track with considerable momentum. If it rolls at the samespeed but has twice as much mass, its momentum is
doubled
When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannonis due to different
masses
From the same height you simultaneously drop a lightweight tennis ball and aheavyweight bowling ball. When they hit the floor they have the same
speed