How Efficient Are Human Leg Muscles?

[coconut62]

Please refer to the image attached.

For Q5, I did it like this:

Output energy = (50kg x 10 x 0.35metre) x 30times x 4minutes

And divide the answer by 120kJ.

The percentage I got is 17.5 Joules but the answer is 15J.

Did I do anything wrong?

For Q6, the temperature should fall, correct?

Thanks in advance.

 

[ehild]

The muscles did work and produced heat. So the input energy is work+heat. The efficiency is output energy divided by input energy.

ehild

 

[coconut62]

But there are no informations about heat.

 

[ehild]

But there are no informations about heat.

Read the problem text: "The muscles generate 120 kJ heat".

ehild