PHY SCI HW 6
It takes 40 J to push a large crate 4 m across a floor. The force exerted on the crate is
10 N.
A melon is tossed straight upward with 100 J of kinetic energy. If air resistance is negligible the melon will return to its initial level with a kinetic energy of
100 J.
A shopping cart moves with a kinetic energy of 40 J. If it moves at twice the speed, its kinetic energy is
160 J.
If you exert 100 J to lift a box in 50 s your power output is
2 W.
A 2-kg mass that weighs 20 N has 40 J of potential energy relative to the ground. What is its height?
2 m
A music console is pushed 2 m by a force of 20 N. The work done on the console is
40 J
A bow is drawn so that it has 40 J of potential energy. When the arrow is fired its kinetic energy is ideally
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.
Which has greater kinetic energy: a car traveling at 30 km/h or another car of half the mass traveling at 60 km/h?
The 60-km/h car
A moving object has
all of the above
The amount of potential energy possessed by an elevated object is
equal to the work done in lifting it.
A melon is projected into the air with 100 J of kinetic energy in the presence of air resistance. When it returns to its initial level its kinetic energy is
less than 100 j
An object may have potential energy because of its
location
An object that has kinetic energy must be
moving.
Work is done by gravity on a bowling ball that rolls
on a sloped surface.
You do work on a cart loaded with groceries. If you do this work in one-third the usual time, you expend
three times the usual power.
A 1000-kg car and a 2000-kg car are hoisted the same vertical distance in a service station. Raising the more massive car requires
twice as much work
When you push an object a certain distance while applying twice the force, you do
twice as much work
If you push an object twice as far while applying the same force, you do
twice as much work.
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.
If you do work on an object in half the time, your power output is
twice.
Power is defined as the
work done divided by the time to do the work.