Question

a bullet of mass 4.2g is moving at certain velocity.if all kinetic energy is converted to heat the amount of energy liberated is 20 cal then initial velocity of bullet is​

Answer 1

1/2 mv*2 I -1/2mv*2 f=E

1/2×4.2×v *2-0=20×4.318j

v=86.36/2.1

v=43.18

Answer 2

The initial velocity is 6312.4 m/s.

Explanation:

Given that,

Energy = 20 cal = 83680 J

Mass = 4.2 g

We need to calculate the initial velocity

Using formula of kinetic energy

$K.E=\dfrac{1}{2}mv^2$

$v^2=\dfrac{2K.E}{m}$

Where, m = mass of bullet

v = speed of bullet

K.E = kinetic energy

Put the value into the formula

$v^2=\dfrac{2\times83680}{4.2\times10^{-3}}$

$v=\sqrt{\dfrac{2\times83680}{4.2\times10^{-3}}}$

$v=6312.4\ m/s$

Hence, The initial velocity is 6312.4 m/s.

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Topic : kinetic energy

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