Chris asks…How many times would you need to lift a 1kg weight 60cm against gravity?How many times would you need to lift a 1kg weight 60cm against gravity to burn the 140kcal in a bag of chips?Nancy answers:At about 4.2 kJ per kcal you have a potential food energy of 140 * 4.2 = 588, 000 J
Now the first thing to know is that no machine is perfectly efficient.
Are you an athlete in training or a couch potato? This makes a difference.
Your efficiency may be more or less but if we take it at
