Vocabulary & Concepts
What form of energy is associated with motion?
What must happen for work to be done on an object?
A force must cause displacement
Which energy increases when an object speeds up?
kinetic energy
What usually causes mechanical energy to decrease in real systems?
friction
What equation is used to calculate kinetic energy?
What type of energy depends on an object’s height?
gravitational potential energy
What happens to work if force is perpendicular to motion?
work is zero
Which two factors affect kinetic energy?
mass and speed
What happens to energy “lost” to friction?
it becomes thermal energy
Which equation calculates gravitational potential energy near Earth’s surface?
U=mgh
What quantity describes the rate at which energy is used?
power
Which quantity is measured in joules?
Work (joules)
Which energy changes when an object falls?
GPE decreases
What does efficiency compare?
Useful output energy to input energy
What equation relates work to force and distance when force is parallel to motion?
W=fd
What law states that energy cannot be created or destroyed?
law of conservation of energy
Is work done when holding a heavy object still?
Nope
If two objects have the same speed, which has more KE?
the object with more mass
If efficiency is less than 100%, what must be true?
Some energy was transferred to non-useful forms
What equation is used to calculate power?
P=W/t
What does it mean if work done on an object is negative?
The force opposes the motion
If an object slows down, what can you say about the net work?
net work is negative
At the highest point of a vertical toss, what is the kinetic energy?
zero
Does a system with friction violate conservation of energy?
no
Which equation shows the relationship between net work and kinetic energy?
W net=deltaKE