Question

A block of mass 𝑚 sliding down an incline at constant speed is initially at a height $h$ ℎ above the ground, as shown in the figure above. The coefficient of kinetic friction between the mass and the incline is $\mu$. If the mass continues to slide down the incline at a constant speed, how much energy is dissipated by friction by the time the mass reaches the bottom of the incline?

• A. $\frac{\mu mgh}{\sin \theta }$
• B. $mgh$
• C. $\frac{mgh}{\theta }$
• D. $mgh\sin \theta$

Answer 1

The correct option is B $mgh$

By using work- energy theorem,
$W_{allforces}=\Delta K+\Delta U$
Therefore,
$W_f=\Delta K+\Delta U$
$W_f=0-mgh$
$W_f=-mgh$