Calculating Joe's Climb Efficiency

  • Thread starter lcp1992
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In summary, Joe ascended a small hill from an elevation of 250m to 490m, expending 2.8x10^5J. With a mass of 75kg, his efficiency in climbing was calculated to be 0.63 using the formula %efficiency=useful energy output/total energy input x 100%. This efficiency can be attributed to the fact that human beings, like most machines, are inefficient and use more energy than necessary to complete a task.
  • #1
lcp1992
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Homework Statement


Joe ascends a small hill from an elevation of 250m to an elevation of 490m. In doing so he expends 2.8x10^5J. If Joe's mass is 75kg what is the efficiency of his climb?

Homework Equations


W= change in E= change in Ek + change in Ep
Ep= mgh
Ek= 0.5mv^2
%efficiency=useful energy output/total energy input x 100%

The Attempt at a Solution


should i use the work energy theorem to solve the problem?
 
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  • #2
Welcome to PF!
I wouldn't use the theorem since there is no kinetic energy involved. The "useful energy" is just mgh.
 
  • #3
Iused the mgh formula, but I couldn't get the answer which is 0.63
 
  • #4
If the climber has gained the energy 'mgh' from climbing the hill, and the energy exerted is 2.8x10^5J, then his efficiency would be what?
 
  • #5
0.63 is the efficiency
 
  • #6
So you got it? It certainly works out to .63 for me. If it didn't for you, show your work.
 
  • #7
I got it but I am still confused so the work is total energy input and the energy is the useful energy , why?
 
  • #8
lcp1992 said:
I got it but I am still confused so the work is total energy input and the energy is the useful energy , why?

You only need to do mgh amount of work to climb a hill up to height h. But human beings (like most machines) are inefficient, which means that they will actually use MORE energy than this during the trip. The excess energy is wasted (as heat or whatever). That's why the input energy is larger than the output (useful) energy which actually went into doing the work necessary to get up the hill.
 
  • #9
thanks!
 

What is "Calculating Joe's Climb Efficiency"?

"Calculating Joe's Climb Efficiency" is a scientific method used to determine the efficiency of a person's climbing ability. It involves measuring the amount of work performed and the time taken to complete the climb, and then using a formula to calculate the person's efficiency.

Why is it important to calculate climb efficiency?

Calculating climb efficiency can help climbers understand their strengths and weaknesses, and track their progress over time. It can also be used to compare different climbing techniques and equipment to determine which ones are most efficient.

What factors are taken into account when calculating climb efficiency?

The main factors that are considered when calculating climb efficiency are the distance climbed, the weight of the climber, and the time taken to complete the climb. Other factors that can affect efficiency include the terrain, weather conditions, and the type of climbing equipment used.

How is climb efficiency calculated?

The most commonly used formula for calculating climb efficiency is the Watts/kg formula, which divides the work (in Watts) by the weight of the climber (in kg). This gives a number that represents how many Watts of energy are used for each kilogram of body weight. The higher the number, the more efficient the climb.

Are there any limitations to calculating climb efficiency?

Yes, there are some limitations to calculating climb efficiency. The formula does not take into account factors such as technique, experience, and mental strength. It also assumes a linear relationship between work and time, which may not always be accurate. Additionally, the formula does not consider the difficulty or grade of the climb, which can greatly affect efficiency.

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