What is the power output needed to bike uphill at a steady speed of 4.5 m/s?

  • Thread starter Thread starter Symstar
  • Start date Start date
  • Tags Tags
    Power
Click For Summary

Homework Help Overview

The problem involves calculating the power output required for a bicyclist to climb a hill at a steady speed of 4.5 m/s, given a specific incline and total mass. The context includes concepts from mechanics, particularly relating to forces and power in the context of motion on an incline.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate power output using the relationship between work and time, incorporating gravitational forces acting on the cyclist. Some participants question the validity of the original poster's calculations and the assumptions made regarding forces when transitioning from coasting downhill to climbing uphill.

Discussion Status

The discussion is ongoing, with some participants affirming the original poster's calculations while others suggest that additional factors, such as retardant forces, need to be considered when climbing uphill. There is no explicit consensus on the correctness of the original calculation, and the original poster plans to seek further clarification from a professor.

Contextual Notes

Participants note that the problem may involve additional complexities due to the transition from coasting downhill to climbing uphill, which could affect the forces at play and the required power output.

Symstar
Messages
16
Reaction score
0

Homework Statement


A bicyclist coasts down a 6.0 degree hill at a steady speed of 4.5 m/s.
Assuming a total mass of 60 kg (bicycle plus rider), what must be the cyclist's power output to climb the same hill at the same speed?

Homework Equations


Newton's 1st law
P=W/t

The Attempt at a Solution


P=\frac{W}{t}=F \cdot v

Set x-axis along incline...
F-mg\sin\theta=0
F=mg\sin\theta
P=mg\sin\theta*4.5 = 276.6 W

To 2 sigfig = 280 W

Is this correct? I'm being told it is the wrong answer...
 
Physics news on Phys.org
It looks right.
Who told you that is not?
 
The site where I submit my homework =/ I can't find any problem with it either, so I don't know what's up - guess I'll go ask the professor tomorrow. Thanks for checking my work and please let me know if you do think of somewhere I went wrong.
 
Just an update... since the rider coasts down the hill but isn't accelerating, we must assume that there is a retardant force which must also be factored in when going uphill. This is where I went wrong. Kind of a trick question... blah!
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 8 ·
Replies
8
Views
8K