Work
In order for work to be done, what must be true of force and displacement
they must be parrallel
they should be in same direction
if an object is not moving it has _____ KE
0
Potential energy is the energy due to ____
position
When is mechanical energy conserved?
when there is no friction
The unit for power is called the
Watt. Know the other forms.
If the sign of work is positive, this means that .....
force and displacement are in same directions.
The sign of kinetic enrgy is ______ positive
always
The work done lifting an object is _____ its change in potential energy
equal to
Which of the following is a form of mechanical energy a. Internal b. Electrical c. Chemical potential d. Gravitational potential
D
If a job done two different ways requires the same amount of work, how is power affected
depends on the time
a car slows down on a flat road. is work being done
yes
Ball A has double the mass of ball B. What is the ration of KE of A to B
2:1
What are the units for a spring constant
N/m
Friction converts kinetic energy to ___
Heat
The distance an object is pushed doubles while the time it takes to do the work is cut in half, what happens to the power
4 times greater
What is the units of Work
Joules, N*m or Kgm^2/s^2
If the velocity of an object triples its KE will be
nine times greater
Potential energy is always measured relative to _____
an arbitrary zero level
from ground
if friction is negligible, the what will be the kinetic enregy of an arrow that is shot out of a bow that has a potenital energy of 70 J
70 J
If the power an object has triples what will happen to its speed
it will triple
If speed is constant during the motion, will it affect how much work is done
no
If friction is the only force acting on an object will its KE will?
decrease
if the length of a stretched spring is cut in half, its elastic potential energy would be _________
1/4
Energy is changed from one form to another with no net loss or gain is ________ (T or F)
Always true
The kilowatt-hour is a measure of _____
Energy