91影视

The mass of the person is\(m = 52\;{\rm{kg}}\).

The radius of the circular motion traced by the pedal is\(r = 17{\rm{cm}}\; = 0.17\;{\rm{m}}\).

Torque is defined as the measure of the force that causes an object to rotate about an axis. It is also called the rotational equivalent of linear force.

Mathematically, torque is represented as follows:

\(\begin{aligned}{c}\vec \tau = \vec r \times \vec F\\\left| \tau \right| = rF\sin \theta \end{aligned}\) 鈥� (i)

Here, Fi is the applied force, and r is the perpendicular distance between the point about which the torque and point of application of force are calculated.

The maximum torque will be exerted by the force of her weight. It means that the direction of her weight will be tangential (making a right angle) to the axis of rotation.

\( \Rightarrow \theta = {90^{\rm{o}}}\)

From equation (1),

\(\begin{aligned}{c}\left| \tau \right| &= rF\sin \theta \\ &= r\left( {mg} \right)\sin \theta \\ &= \left( {0.17\;{\rm{m}}} \right)\left( {52\;{\rm{kg}}} \right)\left( {9.8\;{\rm{m/}}{{\rm{s}}^2}} \right)\sin {90^{\rm{o}}}\\ &= 86.63\;{\rm{m}}\;{\rm{N}}\end{aligned}\)

Thus, the maximum torque exerted by the person is 86.63 m N.

The person can exert more torque by pushing down one leg with her weight and muscles and raising her centre of mass.

She can also use toe straps to pull the other leg up as she pedals which increase the downward force of her legs.