A 100 kg box slides with constant velocity down a ramp inclined at 20 degrees, with the horizontal. Find the frictional force acting on the box.

1 answer

Wb = mg = 100kg * 8.8N/kg = 980 N. = Wt. of box.

Fb = 980N @ 20 Deg. = Force of the box.
Fp = 980*sin20 = 335.2 N. = Force parallel to ramp.
Fv = 980*cos20 = 920.9 N. = Force perpendicular to ramp.

Fk = Force of kinetic frictin.

Fn = Fp - Fk = ma
335.2 - Fk = 100*0.
335.2 - Fk = 0.
Fk = 335.2 N.