Physics

Problem

A block of mass

m

is pulled \,up a friction-free ramp that makes an angle

\theta

with the horizontal. The pulling force

F

acts parallel to the surface of the ramp, and the block moves at constant speed. Which expression gives the magnitude of

F

? a)

m g

m g \sin\theta

m g \cos\theta

\dfrac{m g}{\sin\theta}