Download Energy - Teach-n-Learn-Chem

(a) Radiant energy
(c) Chemical energy
(b) Thermal energy
(d) Nuclear energy
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(e) Electrical energy
Potential energy
Energy in
kinetic energy
Energy out
kinetic energy
The energy something possesses due to its motion, depending on mass and velocity.
Energy
A
C
B
Kinetic Energy – energy of motion
KE = ½ m v 2
mass
velocity (speed)
Potential Energy – stored energy
Batteries (chemical potential energy)
Spring in a watch (mechanical potential energy)
Water trapped above a dam (gravitational potential energy)
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
BUS
KE = ½ m v 2
KE(bus) = ½ (10,000 lbs) (0.5 mph)2
BULLET
KE = ½ m v 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
lower temperature
Fractions of particles
higher temperature
minimum energy
for reaction
Kinetic energy
Kinetic Energy and Reaction
Rate
lower temperature
Fractions of particles
higher temperature
minimum energy
for reaction
Kinetic energy
Hot vs. Cold Tea
Many molecules have an
intermediate kinetic energy
Low temperature
(iced tea)
High temperature
(hot tea)
Percent of molecules
Few molecules have a
very high kinetic energy
Kinetic energy