Question

A boy named Raman has gun with laed bullets . He fired the shot with a velocity of 200 m/s and the bullet is bought to rest after hitting the target . Calculate the rise in temprature of the bullet assuming that the all the heat developed remains in the bullet. Specefic heat of lead is given 127.7 j/kg K .

Answer 1

Heya.........!!!!

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Given In the question :-

• Initial velocity of bullet ( u ) = 200 m/s
• Final velocity of bullet ( v ) = 0 { bullet is bought to rest } .

• Specefic Heat of copper = 127.7 j/Kg K .

Mass is not mentioned in the question so let the mass be ( m ) .

Let us take out ∆ KE i.e decrease in kinetic Energy or we can say work done ( W ) :-

W = 1/2 mu^2 - 1/2mv^2

W = 1/2 × m × 200^2

=> W = 2 × 10^4 m J ( m is the mass ) .


In the question it is mentioned that whole energy ( W ) has been changed to heat ( Q ) .

=> Q = W

and we have Q = ( 2 × 10^4m ) J

We have to take out rise in temprature of bullet ( ∆ T )

=> Q = mc∆T
=> Q = m × 127.7 × ∆ T
=> 2 × 10^4m = m × 127.7 × ∆ T

=> ∆ T = 2 × 10^4 / 127.7

♦ ∆T => 156.6 K .


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