Question

Question
Two students in bumper cars want to prove conservation of momentum. They collide their bumper cars. The first bumper car has a mass of 120 kg
and was moving with a velocity of 4.0 m/s
before the collision and with a velocity of −2.0 m/s
after the collision. The second bumper car has a mass of 90 kg
and was moving at a velocity of −5.0 m/s
before the collision. To prove conservation of momentum, what must the velocity of the second bumper car be after the collision?(1 point)
Responses

1.0 m/s

1 point 0 meters per seconds

2.7 m/s

2 point 7 meters per seconds

3.0 m/s

3 point 0 meters per seconds

2.3 m/s

2 point 3 meters per seconds
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Answer 1

Use conservation of momentum:

m1 v1 + m2 v2 = m1 v1' + m2 v2'

120(4.0) + 90(−5.0) = 120(−2.0) + 90 v2'

480 − 450 = −240 + 90 v2'

30 = −240 + 90 v2' → 90 v2' = 270 → v2' = 3.0 m/s

Answer: 3.0 m/s.