Question

A 42 kg block of ice moving on rough horizontal surface stops due to friction, after some time. If the initial velocity of the decelerating block is 4 $m{s}^{-1}$, the mass of ice (in kg) that has melted due to the heat generated by the friction is (latent heat of ice is $3.36\times {10}^{5}Jk{g}^{-1}$)

• A. ${10}^{-3}$
• B. $1.5\times {10}^{-3}$
• C. $2\times {10}^{-3}$
• D. $2.5\times {10}^{-3}$

Answer 1

The correct option is A ${10}^{-3}$

The change in the kinetic energy of the ice is,
$\frac{1}{2}m{v}^2$
This energy is required to melt the ice.
$\frac{1}{2}\times 42\times 4^2=m^{\prime }\times 3.36\times {10}^5$
Thus, m' = 1 g