Work, Energy and Power — Question 22

Given,

Mass = 50 g = 0.05 kg

Velocity = 500 m / s

Distance (S) = 10 cm = 0.1 m

(a) The kinetic energy possessed by the bullet = $\dfrac{1}{2}$ × mass × (velocity)²

Substituting the values in equation we get,

$KE = \dfrac {1}{2} \times 0.05 \times 500^2 \\[0.5em] KE = \dfrac {1}{2} \times 0.05 \times 250000 \\[0.5em] \Rightarrow KE = 6250J \\[0.5em]$

(b)

$\text{Retarding Force} = \dfrac{\text{Work done by bullet}}{\text{distance}} \\[0.5em] = \dfrac{6250}{0.1} \\[0.5em] = 62500N \\[0.5em]$

∴ Average retarding force offered by target = 62500N