A block slides down an incline of angle ß at a constant speed. The force pulling it down the incline is?

Question

a) FN

b) Ff

c) Fgcos ß

d) Fgsin ß

Answer 1

One way to recognize the answer quickly is to ask what would happen if the angle were nearly 0.

There would be virtually no component of the gravitational force acting in the direction parallel to the plane, so we want the sine function, which is near 0, not the cosine function, which is near 1.