30°
10 kg
Weight mg resolves into a component along the slope (mg sinθ, drives motion) and perpendicular to it (mg cosθ, balanced by the normal force). The slope is frictionless.
Weight (mg)
Parallel & normal components
mg sinθ
–
mg cosθ (Normal)
–
Acceleration down the slope
–
90°
50 N
0.25 m
Moment (torque) about the nut = F × r × sinθ. Only the component of force perpendicular to the wrench contributes; a force applied along the handle (θ = 0° or 180°) produces zero turning effect.
Applied force
Perp. & along-wrench components
Perpendicular comp. (F sinθ)
–
Along-wrench comp. (F cosθ)
–
Moment, M = F·r·sinθ
–
30°
40 N
5 m
Only the component of force along the direction of motion does work: W = F·d·cosθ. At θ = 90° the force does no work; beyond 90° it does negative work.
Applied force
Component along d
Displacement
Component along d (F cosθ)
–
Perpendicular comp.
–
Work done, W = F·d·cosθ
–