energy copyright © 2007 pearson benjamin cummings. all rights reserved. (a) radiant energy(b)...
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Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.
(a) Radiant energy (b) Thermal energy
(c) Chemical energy (d) Nuclear energy (e) Electrical energy
The energy something possesses due to its motion, depending on mass and velocity.
Potential energy
Energy in Energy out
kinetic energy kinetic energy
Energy
Kinetic Energy – energy of motion
KE = ½ m v 2
Potential Energy – stored energy
Batteries (chemical potential energy)
Spring in a watch (mechanical potential energy)
Water trapped above a dam (gravitational potential energy)
mass velocity (speed)
B
AC
School Bus or Bullet?
Which has more kinetic energy; a slow moving school bus or a fast moving bullet?
Recall: KE = ½ m v 2
KE = ½ m v 2 KE = ½ m v
2
BUS BULLET
KE(bus) = ½ (10,000 lbs) (0.5 mph)2 KE(bullet) = ½ (0.002 lbs) (240 mph)2
Either may have more KE, it depends on the mass of the bus and the velocity of the bullet.
Which is a more important factor: mass or velocity? Why? (Velocity)2
Kinetic Energy and Reaction Rate
Kinetic energy
Fra
ctio
ns o
f pa
rtic
les
lower temperature
higher temperature
minimum energyfor reaction
Kinetic Energy and Reaction Rate
Kinetic energy
Fra
ctio
ns o
f pa
rtic
les
lower temperature
higher temperature
minimum energyfor reaction