Work Bicycle Problem: Calculate Work Done in Each Stroke

  • Thread starter Thread starter timficker
  • Start date Start date
  • Tags Tags
    Bicycle Work
Click For Summary

Homework Help Overview

The problem involves calculating the work done by a cyclist pedaling a bicycle uphill, specifically focusing on the force exerted during each stroke and the distance associated with that force. The subject area relates to mechanics, particularly work and force in the context of circular motion.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate work by considering force and circumference but expresses confusion about the correct approach. Some participants suggest thinking about torque and the relevant equations, while others reflect on the relationship between force, distance, and the specific context of the pedal stroke.

Discussion Status

The discussion includes attempts to clarify the relationship between force and distance in the context of work done during a pedal stroke. Some participants have arrived at an answer but express uncertainty about the reasoning behind it. There is an ongoing exploration of concepts related to torque and the mechanics of work.

Contextual Notes

Participants note that the concept of torque has not yet been covered in their studies, which may influence their understanding of the problem. There is also mention of confusion regarding the appropriate distance to use in the work calculation, whether it should be the diameter or the circumference.

timficker
Messages
2
Reaction score
0

Homework Statement



In pedaling a bicycle uphill, a cyclist exerts a downward force of 500N during each stroke. If the diameter of the circle traced by each pedal is 38cm, calculate how much work is done in each stroke.

Homework Equations



??

The Attempt at a Solution



I'm at a loss, I thought that I could multiply the F * circumference but that didn't work. I don't know where to start. Can anyone help me?

Thanks.
 
Physics news on Phys.org
Hi timficker, welcome to PF. Think "torque" and "work done by a torque". What are the relevant equations?
 
Well, I figured it out finally. We haven't come to torque yet, in a couple weeks. Although I got the answer it was only due to guessing. I don't really understand how it could be true.

But the answer came from F*diameter. I don't know how this could be because I thought the work was the force times the distance traveled which in this case would be the circumference.

Thanks for your help.
 
timficker said:
Well, I figured it out finally. We haven't come to torque yet, in a couple weeks. Although I got the answer it was only due to guessing. I don't really understand how it could be true.

But the answer came from F*diameter. I don't know how this could be because I thought the work was the force times the distance traveled which in this case would be the circumference.

Thanks for your help.
The result can be derived quite easily if you knew about torques. Since you don't, here is a different way to look at it. Work is done when you push down on the pedal, i.e. during the downward stroke only. The displacement is the diameter and the force is F down in the same direction as the displacement. Therefore the work done is Force*Diameter.

Don't forget that it is only the component of the force parallel to the displacement that does work and in this case the force is always down.
 

Similar threads

Replies
5
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 58 ·
2
Replies
58
Views
6K
Replies
7
Views
2K
Replies
3
Views
2K
Replies
3
Views
2K
Replies
37
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 15 ·
Replies
15
Views
5K