Engineering
Physics
Work Done by a Constant Force
Collision
Momentum and Energy Conservation for System of Particles
Question
A 80 kg man is riding on a 40 kg cart travelling at a speed of 2.5m/s on a frictionless surface. He jumps off the cart such that his velocity just after jump is zero with respect to ground. What is the work done by the man (in J) on the system during the jump?
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Solution
By conservation of linear momentum along the horizontal direction.
(80 + 40) 2.5 = 40 × v
v = 7.5 m/s
w = Δk = 1/2 × 40 × (7.5)2 – 1/2 × 120 × (2.5)2 = 750 J