Answer:
1,902 times
Explanation:
The work done to raise the bar is given by
W = mgh
the given mass is 26 kg and the height the bar is raised is .65 m so we get
W = 26 kg * 9.8 m/s^2 * .65 m
= 165.62 J
If we assume that efficiency is 25%, we divide by .25 to get the total energy consumed. If we assume efficiency is 100%, then work done would be equal to the total energy consumed because you would divide work done by a factor of 1 which doesn't change the value
total energy consumed (when efficiency is 25%) = Work/Efficiency
= 165.62 J / .25
= 662.48 J
I will use assume that the energy content of one slice of pizza is 1260 kJ (which converts to 1,260,000 J)
To find the number of times (N) the weightlifter would have to repeat the same exercise to burn off the energy in one slice of pizza -
662.48 J * N = 1,260,000 J
N = 1,260,000 J / 662.48 J = 1,901.94 = 1,902 times
