a bullet of mass m = 1g and speed v = 400 m/s passes completely through a pendul

Question

a bullet of mass m = 1g and speed v = 400 m/s passes completely through a pendulum bob of mass M =1 kg. The bullet emerges with a speed of V/2.

A) Find the velocity of the bob just after impact with the bullet using the principle of conservation of momentum

B) Calculate the energy of the system before the collision (Eo = Ko bullet) and the energy of the system just after the collision (Ef = Kf bullet + Kbob).

C) Show that energy is not conserved during the collision by finding the amount of energy lost during the collision? write this as a percent energy lost.

Explanation / Answer

A) mometum conservation of the system(bullet+bob)

Pi = Pf

=> 0.001*400 = 1*Vbob + 0.001*200

=> Vbob = 0.2 m/s

B) E0 = 1/2mV^2 = 1/2*(0.001)*(400)^2 = 80 j

Ef = 1/2m(V/2)^2 + 1/2*MVbob^2 = 1/2*(0.001)*(200)^2 + 1/2*1*((0.2)^2 = 20.02

C) Ef < E0 => energy is not conserved

% loss = 60/80*100 = 75%

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