A block of mass m slides from rest down an inclined plane of length $s$ and height $h$. If $F$ is the magnitude of the force of kinetic friction acting on the block as it slides, then the kinetic energy of the block when it reaches the bottom of the incline will be equal to
A) $mgh$
B) $mgh-Fh$
C) $mgh-Fs$
D) $mgs-Fs$
A) $mgh$
B) $mgh-Fh$
C) $mgh-Fs$
D) $mgs-Fs$
Since a nonconservative force (namely, friction) is acting during the motion, use the modified Conservation of Mechanical Energy equation.
$$K_{\mathrm{i}}+U_{\mathrm{i}}+W_{\mathrm{friction}}=K_{\mathrm{i}}+U_{\mathrm{f}}$$
$$0+mgh-Fs=K_{\mathrm{f}}+0$$
$$mgh-Fs=K_{\mathrm{f}}$$