A 2 kg cart moving at 3 m/s collides inelastically with a stationary 1 kg cart and they stick together. What is their common velocity after the collision?
Show the answer and explanation
Correct answer
B. 2 m/s
Principle or equation
Conservation of momentum: m1*v1 + m2*v2 = (m1 + m2)*v_final. Since v2 = 0, v_final = m1*v1 / (m1 + m2).
Why this answer is correct
Substitute m1 = 2 kg, v1 = 3 m/s, m2 = 1 kg: v_final = (2*3) / (2+1) = 6/3 = 2 m/s.
Example
A 5 kg object moving at 2 m/s hits a 3 kg object at rest and they stick; final velocity = (5*2)/(5+3) = 10/8 = 1.25 m/s.
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