A 0.20 kg air-track glider moving at 1.20 m/s bumps into a0.600 kg glider at rest. a) find the total kinetic energy after collision if the collision is elastic. b) find the total kinetic energy after collision if the collision is completely inelastic.

Mass of the air-track glider, ma=0.2 kg

Spead of the air-track glider, v1=1.20 m/s

Mass of bumps = 0.60 kg

Spead of the bumps, v1 = 0

An elastic collision conserves mechanical energy

KE = 1/2 ma*v1^2

Substitute 1.20 for v1 and 0.20 for ma

1/2 0.20 (1.20) ^2

=0.144 J

Totally inellastic collision coservation of momentum

M1V1 + M2V2 = (M1M2) V3

0.20 (1.20) + 0.600 = 0.800 (V3)

V3 = 0.300

So

KE = 1/2 mv^2

1/2 (0.800) (0.300) ^2 = 0.036 J

Notice that 3/4 of the original KE is lost in this collision.