Momentum is conserved in collisions Thus pinitial = pfinal Bouncy: mv + m2v2 = m

ID: 1371754 • Letter: M

Question

Momentum is conserved in collisions

Thus

pinitial = pfinal

Bouncy: mv + m2v2 = m vf + m2 v2f

Sticky: mv + m2v2 = (m + m2) vf

mcar1 300 gr

mcar2 500 gr

Kinetic energy is ONLY conserved for elastic

collisions (no bending, no sticking, no appreciable noise, etc.)

KEinitial KEfinal

Bouncy: ½m1v12 + ½m2v22 = ½m1v1f2 + ½m2v2f2

Sticky: ½m1v12 + ½m2v22 ½(m1 + m2) vf2

In Part 1, cars impact and bounce, car 2 is

initially at rest while initial vcar1 = 2 m/s.

(a) If final vcar1 = -½ m/s, what is final vcar2?

(b) Calculate initial KE of the

system in part 1.

system in part 1

In part 2, cars impact and stick, initial vcar1 is

2.00 m/s while car2 is initially at rest.

(a) What is the velocity of the system

immediately following the collision?

(b) Calculate initial KE of the

system in part 2

1)
Using momentum coservation,

300 x 2 + 500x0 = (300 x -0.50) + 500v2

v2 = 1.5 m/s

b) initial KE = 0.300 x 2^2 /2 + 0 = 0.6 J

c) final KE = 0.300x0.5^2 /2 + 500 x 1.5^2 /2 = 0.6 J

a) Using momentum coservation,

300 x 2 + 500x0 = (300 + 500)v

v = 0.75 m/s

b) initial KE = 0.300 x 2^2 /2 = 0.6 J

c) final KE = (0.3 + 0.5) x 0.75^2 /2 = 0.225 J

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