1kg of fat is equal to 30MJ of energy.the efficiceny of converting fat to energy is 20%. suppose you life a mass of 12kg 2.0m vertically,500 times, how much work do you do?

work=mgh*500

Some will argue about the down stroke, what happens to that energy. But the body does not recycle it.

if all the energy used to do the work comes from the burning fat how much fat is used ?

To calculate the work done, we need to determine the amount of energy required to lift the mass.

First, let's calculate the potential energy (PE) needed to lift the mass vertically by 2.0 meters. The equation for potential energy is: PE = mgh, where m is the mass in kilograms, g is the gravitational acceleration (approximately 9.8 m/s² on Earth), and h is the height in meters.

PE = (12 kg) x (9.8 m/s²) x (2.0 m)
PE = 235.2 Joules

Now, let's find out how many times the mass is lifted. You mentioned it is lifted 500 times.

Total work done = (Potential energy per lift) x (Number of lifts)

Total work done = 235.2 J x 500
Total work done = 117,600 Joules

Therefore, the amount of work done in lifting a mass of 12kg 2.0m vertically, 500 times, is 117,600 Joules.