Conservation of energy/ efficiency question.

In summary, the climber's gravitational potential energy increased from 14000 J to 21 000 J while climbing a cliff. She expended 18 000 J of energy during this activity. The efficiency of this process is 61%.
  • #1
maccha
53
0

Homework Statement



A climber's gravitational potential energy increases from 14000 J to 21 000 J while climbing a cliff. She expends 18 000 J of energy during this activity. What is the efficiency of this process?


Homework Equations



Efficiency= useful output/ total input

Total energy before = total energy after

The Attempt at a Solution



Well, I've been able to solve all other efficiency/ conservatino of energy questions but for some reason I just don't understand this one. I don't understand what to consider as the input or the useful output energy. Thanks for your help!
 
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  • #2
What was her change in potential energy? Isn't that the useful output?

The work gone into increasing potential energy?
 
  • #3
Okay well then useful output would be 7 000 J / 14 000 J (input), and efficiency would be 50 % ? But the answer says it is 61 %.
 
  • #4
No. She expended 18,000 J not 14,000.
 
  • #5
Oh! Okay. Still doesn't work with the answer though ah.
 
  • #6
maccha said:
Oh! Okay. Still doesn't work with the answer though ah.

It is 1 - the answer.

I think the answer may be wrong?
 
  • #7
Yeah we have an exam review booklet which said that was the answer, but I just found the same exam on the internet and it said yours was right, so the booklet answer was wrong. Thanks!
 
  • #8
That's a relief. Wouldn't make sense otherwise.

Good luck.
 

FAQ: Conservation of energy/ efficiency question.

What is the law of conservation of energy?

The law of conservation of energy states that energy cannot be created or destroyed, but can only be transformed from one form to another.

How does conservation of energy apply to everyday life?

Conservation of energy applies to everyday life in many ways, such as when we use appliances, drive cars, or even walk. In all these cases, energy is being transformed from one form to another, but the total amount of energy remains constant.

What is energy efficiency?

Energy efficiency is the use of technology and practices that reduce the amount of energy required to perform a specific task or function. This helps to conserve energy and reduce waste.

How can I improve energy efficiency in my home?

There are many ways to improve energy efficiency in your home, such as using energy-efficient appliances, sealing air leaks, using natural lighting, and adjusting the thermostat. Making small changes can make a big difference in reducing energy consumption.

Why is it important to conserve energy?

Conserving energy is important for several reasons. It helps to reduce the use of finite resources, lower greenhouse gas emissions, and save money on energy bills. Additionally, conserving energy can help to protect the environment and promote sustainability for future generations.

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