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Solved: Professional Application Military rifles have a
Chapter 8, Problem 14(choose chapter or problem)
Problem 14PE
Professional Application Military rifles have a mechanism for reducing the recoil forces of the gun on the person firing it. An internal part recoils over a relatively large distance and is stopped by damping mechanisms in the gun. The larger distance reduces the average force needed to stop the internal part. (a) Calculate the recoil velocity of a 1.00-kg plunger that directly interacts with a 0.0200-kg bullet fired at 600 m/s from the gun. (b) If this part is stopped over a distance of 20.0 cm, what average force is exerted upon it by the gun? (c) Compare this to the force exerted on the gun if the bullet is accelerated to its velocity in 10.0 ms (milliseconds).
Questions & Answers
QUESTION:
Problem 14PE
Professional Application Military rifles have a mechanism for reducing the recoil forces of the gun on the person firing it. An internal part recoils over a relatively large distance and is stopped by damping mechanisms in the gun. The larger distance reduces the average force needed to stop the internal part. (a) Calculate the recoil velocity of a 1.00-kg plunger that directly interacts with a 0.0200-kg bullet fired at 600 m/s from the gun. (b) If this part is stopped over a distance of 20.0 cm, what average force is exerted upon it by the gun? (c) Compare this to the force exerted on the gun if the bullet is accelerated to its velocity in 10.0 ms (milliseconds).
ANSWER:
Solution
Step 1
a) We need to find out the recoil velocity of the plunger.
From conservation of momentum
......(1)
Mass of the plunger
Mass of the bullet
Initial velocity of the plunger
Initial velocity of the bullet
final velocity of the bullet
Final velocity of the plunger is nothing but the recoil velocity.
From equation (1)
The recoil velocity of the plunger is