A bicycle pedal is pushed by a foot with a 60-N force as shown. The shaft of the pedal is 16 cm long. Find the magnitude of the torque about P.

Solution:

Torque = Force × length of the lever arm (shaft in this case)

Torque is the cross-product of force and length.

The formula for finding the magnitude of the torque (𝓣) is given as:

𝓣 =  rFsin θ

r = radius/length of the shaft which connects the pedal with the fulcrum = 16 cm = 0.16 m

F = Force  = 60 N

Θ = angle between F and the lever arm = 70° + 10° = 80°

Torque (𝓣) = 0.16  ×  60  × Sin 80°

    =  0.16 × 60 × 0.985 Newton-meter

    = 9.456 N-m

A bicycle pedal is pushed by a foot with a 60-N force as shown. The shaft of the pedal is 16 cm long. Find the magnitude of the torque about P.

Summary:

The magnitude of the torque about point  P is 9.456 N-m