You do 25 J of work to move a 4 N object 5 meters. What is your efficiency?
1 Answer
Jun 20, 2018
0.8 or 80%
Explanation:
Here, the total amount of energy provided by your body is 25 J. However the amount of energy required to move the object (useful energy) through 5 metres is 20 J. The other 5 J will be wasted and converted to other forms like heat in our muscles.
How did I get 20 J?
It's known that:
Work done = Energy transferred
Here, the work done is the product of force and displacement:
So:
W= 4 x 5 = 20 J
Now what's the efficiency?
Here it is:
Useful output energy/ Total input energy
So:
Or: