3 ms·
> Why not lift something REALLY heavy and let gravity spin a gearbox on the way down? Because lifting something that’s heavy doesn’t store much energy (or, sta
by Someone 4y ago
> Why not lift something REALLY heavy and let gravity spin a gearbox on the way down?
Because lifting something that’s heavy doesn’t store much energy (or, stated alternatively, 1kWh is a lot of energy, compared to human muscles)
https://www.quora.com/How-much-mass-in-kg-can-I-lift-to-1-m-height-with-1-kWh-of-energy https://www.quora.com/How-much-mass-in-kg-can-I-lift-to-1-m-...:
Q: How much mass in kg can I lift to 1 m height, with 1 kWh of energy?
A: Let x kg be the mass to be lifted. The energy required = mgh
x * 9.8kgm²/s² or 9.8x Joules
1 KWH = 3.6 million Joules.
9.8x = 3.6*10⁶ => x = 3.6*10⁶ /9.8 = 3.67*10⁵ kg.
So, that’s about 360,000 kg.
The great pyramid of Giza weighs about 6 billion kg (https://www.egyptabout.com/2019/02/facts-16-fun-facts-about-great-pyramid.html https://www.egyptabout.com/2019/02/facts-16-fun-facts-about-...), so lifting that by a meter would store less than 20,000 kWh.