Physics Exercises/Conservation of Linear Momentum

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[edit] Exercises

conservation ofb linear momentum / recoil velocity=== A motionless catapult was aimed horizontally and fired a 10.0 kg wood block due west at 50 m/s. If the catapult's mass was 250 kg, what is the recoil velocity of the catapult if friction is ignored?

[edit] Solutions

Conservation of linear momentum or recoil velocity=== Conservation of linear momentum is used to solve this problem. The sum of the momentum of the wood block plus the momentum of the catapult must equal the sum of their momentum before the object was fired, which is zero.

M = mass, V = velocity, c = catapult, w = wood block

M_cV_c + M_wV_w = 0

(250.kg)V_c + (10.0kg)(50.0m / s) = 0

V_c = − 2.00m / s

The negative sign indicates that the direction is opposite to the direction of motion of the wood block, which would be east.

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