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Energy
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Identify several forms of energy.
Calculate Kinetic Energy
Distinguish between kinetic energy and Potential energy
• Classify different types of potential Energy
• Calculate Potential energy associated with an object
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Energy: Ability to do work
Different Types of Energy
The Ninja, a roller coaster at Six Flags over Georgia, has
a height of 122 ft and a speed of 52 mi/h. The potential
energy due to its height changes into kinetic energy of
motion.
Energy
Mechanical
Kinetic
Non
Mechanical
Potential
Gravitational
Elastic
Kinetic Energy
Aim:
What is a Kinetic Energy?
Kinetic Energy - the
energy an object
possesses due to
its' motion
KE =
2
(½)mv
Relationship KE/v?
Direct Square
Work and Kinetic Energy
A resultant force changes the velocity of
an object and does work on that object.
v
f
vf
F
F
Work  mv  mv
1
2
2
f
1
2
2
0
Example: A 60.0-kg runner has 1920 joules of
kinetic energy.
At what speed is he running?
KE = (½)mv2
m = 60.0 kg
KE = 1920 J
V=?
1920 J=(1/2)60.0kgV2
1920 J = 30 V2
64.0 = V2
V = 8.00 m/s
A car with a mass of 1,300 kg is going straight
ahead at a speed of 30 m/sec (67 mph).
The brakes can supply a force of 9,500 N.
Calculate:
a) The kinetic energy of the car.
b) The distance it takes to stop.
M= 1300 kg, v= 30m/s, F= 9500 N
KE= ½ m𝑣 2 = ½ (1300kg)(30𝑚./𝑠)2
KE= 5.85x102 J
W= ∆ 𝐾𝐸
2
F.d= ½ (m𝑉𝑓2 )- ½ (m𝑣𝑖2 )= 9500N.d=0J-1/2(1300 Kg)(30m/s)
D= 61.57m