Question

A particle of mass 1 kg was sliding with a velocity of $10m{s}^{-1}$ on a rough floor. It comes to rest after 5 s. The rate at which floor warms up is ___ watt. Assume all kinetic energy of the block is converted to heat.

• A. 5
• B. 8
• C. 10
• D. 12

Answer 1

The correct option is C 10

Given,
Mass $m=1kg$
Velocity $v=10m{s}^{-1}$
Time $t=5s$
The rate at which floor warms up is the rate at which friction does work. Work done by the friction is equal to change in the kinetic energy of the body.
Frictional work $=\frac{1}{2}\times m\times v^2$
$=\frac{1}{2}\times 1\times 100=50J$
So, the rate at which floor warms up would be equal to the rate of frictional work $=\frac{work}{time}=\frac{50}{5}=10W.$