Force exerted on the pedals ?

[juliorgonzalez]

force exerted on the pedals...?

-) A cyclist intends to cycle up a 7.00° hill whose vertical height is 122 m. Assuming the mass of bicycle plus person is 76.2 kg, calculate how much work must be done against gravity. I got this part by multipling the (m)(g)(d)= 91100
If each complete revolution of the pedals moves the bike 5.00 m along its path, calculate the average force that must be exerted on the pedals tangent to their circular path. Neglect work done by friction and other losses. The pedals turn in a circle of diameter 34.6 cm.
I really have no idea . so if u can help me with that
thanx

 

[quinn]

Think about it. You know the required force at the wheels,.. and 1 rev of the pedel = 5 m,.. total path is known,... divide to get the amount of force at the wheels per 1 rev of the pedels,...next use torque conversion to get force at pedals,.. remember 5 m is the outer lever distance,.. so the pedel requires more force than at the wheels

 

[kyle8921]

The force exerted on the pedals is directly related to the work that needs to be done against gravity. As the cyclist pedals, they are applying a force to the pedals which in turn rotates the wheels and propels the bike forward. This force is what allows the cyclist to overcome the force of gravity pulling them back down the hill.

To calculate the average force exerted on the pedals, we can use the formula F = W/d, where F is the force, W is the work, and d is the distance. In this case, the work done against gravity is 91100 J and the distance traveled for each revolution of the pedals is 5.00 m. So, the average force exerted on the pedals would be 91100 J / 5.00 m = 18220 N.

Additionally, we can calculate the force exerted on each pedal separately by dividing the total force by the number of pedals. In this case, if the bike has two pedals, the force exerted on each pedal would be 18220 N / 2 = 9110 N. This force is necessary to overcome the force of gravity and maintain a constant speed while cycling up the hill.

It's important to note that this calculation neglects any other forces that may act on the pedals, such as friction or air resistance. These forces would require additional work to be done and would increase the force needed to be exerted on the pedals.