The length of a bicycle pedal arm is 0.152 m, and a downward force of 129 N is...

P

paddle789

New member
...applied to the pedal by the...? The length of a bicycle pedal arm is 0.152 m, and a downward force of 129 N is applied to the pedal by the rider's foot. What is the magnitude of the torque about the pedal arm's pivot point when the arm makes the following angles with the vertical?
(a) 30°
_________N·m

(b) 90°
_________ N·m

(c) 180°
_________N·m
 
the component of the force perpendicular to the arm times the distance
(a) 129 Sin(30) * 0.152 = 0.5 * 129 * 1.52 = 9.804 N.m
(b) the full torque. 129*0.152 = 19.608 N.m (i.e. sin(90) = 1)
(c) nothing. 0 N.m (i.e. sin(180) = 0

doesn't b and c make sense, and proves a.
 
Back
Top