Q 11-04-036NEETJEE MainTop questionMedium
A $10$ kg block rests on a horizontal floor. The coefficients of static and kinetic friction are $0.5$ and $0.4$. A horizontal push of $30$ N is applied. The frictional force on the block is ($g = 10\ \text{m/s}^2$)
Answer: (A) $30$ N
Concept. Below the limit, static friction just balances the applied force.
Step 1. Limit. $0.5 \times 100 = 50$ N $> 30$ N, so no sliding.
Step 2. Friction. $30$ N.
Answer. $30$ N (Option A).
Solution by Sreeraj P, M.Sc Physics