A bullet of mass 0.012 kg and horizontal speed 70 ms. strike a block of wood of mass 0.4 kg and instantly
comes to rest with respect to the block. The block is suspended from the ceiling by means of this wire.
Calculate the height to which the block rises.
P.T.O.
Answers
Explanation:
A bullet of mass 0.012 kg and horizontal speed 70 m s–1 strikes a block of wood of mass 0.4 kg and instantly comes to rest with respect to the block. The block is suspended from the ceiling by means of thin wires. Calculate the height to which the block rises. Also, estimate the amount of heat produced in the block.
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Initial momentum of system(bullet+block)
= 0.012×70.
final momentum of system=(0.012+0.4)×v.
(where v is the velocity of bullet- block system after the impact.)
According to law of conservation of linear momentum:
0.012×70=(0.012+0.4)×v.
=> v=2.03m/s.
further,
initial KE of system=(1/2)×0.012×70×70
=29.4J
final KE of system =(1/2)×(0.012+0.4)×2.03×2.03=0.848J
HEAT PRODUCED= LOSS IN KE OF SYSTEM.
=> heat produced= 29.4-0.848=28.552J
further,
FROM THE LAW OF CONSERVATION OF ENERGY :
0.848= (0.012+0.4)×g×h.
(where g is acceleration due to gravity and h is the height gained by the system )
=> h= 0.20m