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प्रश्न
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उत्तर
Given, mass m = 25g = `25/1000 "kg" = 1/40 "kg"`
initial velocity u = 600 m/s
final velocity v = 0 m/s
Distance traveled, s = 50 cm = 0.5m
Now, K.E of the bullet = `1/2` mu2 = `1/2 (1/40) (600)`2
or, K.E = 4500 J
let F be the resistive force
According to work energy theorem,
work done = change in K.E
or, work done = `1/2` m(v-u)2 = `1/2 (1/40)` (0 - 600)2 = -4500 J
Also, we know that: work done = force x displacement
`therefore` -4500 = F x 0.5
or, F = `-4500/0.5` = -9000 N
Hence, the resistive force is 9000 N.
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