Question

a block a mass 50kg slides down a plane inclined at an angle 30 to the horizontal. if the coefficient of friction is 0.4 calculate the frictional force btwn the two surfaces (g=10m/s)

Answer 1

The friction force by definition

$$F=\mu N$$

The normal reaction force is given by

$$N=mg\cos\theta$$

So

$$F=\mu mg\cos\theta$$

$$=0.4\times 50\:\rm kg\times 10\: m/s^2\times \cos 30^{\circ}=173.2\:\rm N$$