How many people does it take to build a pyramid?
Stories from Physics
for 11-14
14-16
The Greek historian Herodotus reported that, once the site had been prepared, it took 100,000 men twenty years to build the Great Pyramid. A professor of physics has analysed whether this claim is realistic and estimates that the total work required to construct the Great Pyramid is around 1.3 x 10 13 J. Assuming that one person could do 150 kcal (628 kJ) of work on the pyramid per day, the academic argued that the work could be completed by only 5,700 people over 10 years.

References
How many people does it take to build a pyramid?
A. C. Tort, Work, gravitational energy and the Great Pyramid. Physics Education, vol. 50, no. 5, 2015, pp. 516-520