Question

A lead bullet of $10g$ travelling with $300m/s$ strikes against a block of wood and comes to rest. Assuming $60$% of heat is absorbed by the bullet, the increase in its temperature is (Specific heat of Lead is $150$ Jk$g^{-1}{k}^{-1}$):

• A. ${10}^{0}C$
• B. ${12.5}^{0}C$
• C. ${180}^{0}C$
• D. ${20}^{0}C$

Answer 1

The correct option is C ${180}^{0}C$

Energy absorbed by the bullet$=$$0.6\times$ (Kinetic energy of the bullet)
$mc\Delta T=0.6\left(0.5\right)m{v}^2$
$\Delta T=\frac{\left(0.6\right)\left(0.5\right)\left({300}^2\right)}{150}={180}^{o}C$