• Support PF! Buy your school textbooks, materials and every day products via PF Here!

A simple question

This is an actual question from the past papers. The question is:
It is stated that many forms of transport transform chemical energy into Kinetic energy. Explain why a cyclist traveling at content speed is not making this transformation and explain what transformations of energy are taking place.
I can’t understand why the cyclist is not making this transformation. His K.E. is constant and so is his Gravitational potential energy. But to travel at constant speed he must overcome the resistive forces i.e. energy is being continuously used to work against resistive forces. So that means the chemical energy(which came from the food he ate) is being converted into heat energy(respiration) which is being converted in to mechanical energy of the cyclist which in turn is being converted into K.E. of the cyclist and the cycle and also into heat energy. Therefore ultimately the transformation chemical to KE is taking place. Please tell me where I went wrong.
Thanks in advance for any help that you guys can offer
:approve:
 
Last edited:
1,675
3
You did not go wrong. The problem was probably intended to neglect the forces
of friction and wind resistance.

It should be added that the cyclist would be on level ground.
 

LeonhardEuler

Gold Member
858
1
Actually, he is not converting his energy into kinetic energy, since his speed reamains constant. When he pedals he is turning chemical energy into the heat that is disipated by friction and air resistance. The only time when the cyclist converts chemical energy into kinetic energy is when he speeds up. I don't believe the problem intended to neglect friction and air resistance.
 

Related Threads for: A simple question

  • Posted
Replies
1
Views
906
Replies
14
Views
5K
  • Posted
Replies
8
Views
1K
  • Posted
Replies
6
Views
3K
  • Posted
Replies
5
Views
958
  • Posted
Replies
2
Views
4K
  • Posted
Replies
1
Views
454
  • Posted
Replies
4
Views
1K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top