Needed Power Output on an Incline

  • #1

Homework Statement


A bicyclist coasts down a 7 degree hill at a steady speed of 5 m/s. Assuming the total mass of 75 kg, what must be the cyclist's power output to climb the same hill at the same speed


Homework Equations


power = force * distance / time
force of gravity = mass * gravity


The Attempt at a Solution


At first glance, I just did 75 kg * 9.8 m/s^2 * 5 m * sin(7 degrees) / 1 s, which equaled to about 448 W
But the problem is, if the cyclist was on flat ground, the he/she would need an output of 3675 W, which is far greater 448 W
So then I tried 83 degrees since 90-7=83
When I replaced 7 degrees with 83, I got an output of about 3648 W, which sounds more reasonable to me.
Which answer is right? If neither of them are, what can help me to get the right answer?
 

Answers and Replies

  • #2
Hootenanny
Staff Emeritus
Science Advisor
Gold Member
9,621
6
I would say that your first answer is correct. I'm not sure where your pulling the 3675W on the flat from.
 
  • #3
I would say that your first answer is correct. I'm not sure where your pulling the 3675W on the flat from.

I got it from the situation if the cyclist was going at 5 m/s on flat ground with no incline
 

Related Threads on Needed Power Output on an Incline

  • Last Post
Replies
8
Views
5K
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
4
Views
1K
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
10K
  • Last Post
Replies
5
Views
6K
Replies
2
Views
20K
Replies
3
Views
2K
Top