A particle of mass $m$ at rest on a rough horizontal surface with a coefficient of friction $\mu$ is given a

velocity $u$. The average power imparted by friction before it stops

A force of $(4 \hat{\mathbf{i}}+2 \hat{\mathbf{j}}+\hat{\mathbf{k}}) \mathrm{N}$ is action on a particle of mass 2 kg displaces the particle from a position of $(2 \hat{\mathbf{i}}+2 \hat{\mathbf{j}}+\hat{\mathbf{k}})$ $m$ to a position of $(4 \hat{\mathbf{i}}+3 \hat{\mathbf{j}}+2 \hat{\mathbf{k}}) \mathrm{m}$. The work done by the force on the particle in joules is

The average power generated by a 90 kg mountain climber who climbs a summit of height 600 m in 90 min is (Acceleration due to gravity $=10 \mathrm{~ms}^{-2}$ )