Unit 4 Review
What is the kinetic energy of a 44kg cheetah running at 31 m/s?
21,142J
Kinetic energy (KE)
the energy of an object due to the object's motion.
Gravitational Potential Energy (GPE)
Energy that is due to the gravitational forces between objects. One can also say GPE is energy due to position above the surface of the earth.
Elastic Potential Energy
Energy that is stored by compressing or stretching an object
Energy is measured in?
Joules (J)
Formula to solve for kinetic energy
KE= 1/2(mass x velocity^2)
When ever work is done, energy is _____________ or is _____________ from one system to another.
Transformed, or is Transferred.
A book weighing 14 N is lifted 2 meters. How much work is done?
W= Fd = (14N)(2m)= 28J
Units for power
Watt (W)
The Potential Energy Formula
PE= m x g x h
Chemical Potential Energy
Energy that is due to chemical bonds
The amount of kinetic energy an object has depends on 2 things
The mass of the object, and The velocity at which it is moving
If a 60 watt light bulb does 216,000 J of work, how long has it been turned on?
t=w/p 216,000J/60W = 3,600s
Energy
the ability to do work
Find the kinetic energy of a 50 kg swimmer, swimming at a speed of 4m/s.
400J
Find the potential energy of a 50 kg diver on a 15 meter cliff.
7,350J
System
A group of objects and the factors that affect those objects.
The Law of Conservation of Energy
Energy cannot be created or destroyed
If it takes you 10s to do 150 J of work on a box to move it up a ramp, what is your power output?
P= W/t= (150J)/(10s) = 15W
Formula for power
Power = work/time (P=W/t)
Power
The amount of work done in a certain period of time
Formula for work
Work = force x distance (W=Fd)
Potential energy
energy that is stored due to the interaction between objects.
What is work?
is done on an object when the object moves in the same direction in which the force is exerted.
Units for work
joules (j)
