Question

A block of mass 10 kg is placed on a rough horizontal surface with static friction coefficient equal to 0.5 and kinetic friction coefficient equal to 0.3. The block given a horizontal velocity of 16 m/s towards right direction and a constant horizontal force of $F_0=10N$ is applied to the left. Then choose the correct options :$(g=10m/s^2)$

• A. The instant $t_0$ at which the block stops is 8 sec.
• B. The instant $t_0$ at which the block stops is 4 sec.
• C. The instant $t_0$ at which the block stops is 3 sec.
• D. None of these

Answer 1

The correct option is B The instant $t_0$ at which the block stops is 4 sec.

$\begin{array}{c}\mu =XN\\ =0.3\times 100\\ =30N\\ Now,\\ a=\frac{40}{10}m/s=4m/sretardation\\ theins\tan t{t}_{0}atwhichblockstops,\\ \Rightarrow y_0=a{t}_0\\ \Rightarrow 16=4t_0\\ \Rightarrow t_0=4\sec \\ Hence,optionBiscorrectanswer.\end{array}$