How high can you raise a kilogram of sugar with 1 kWh of electrical energy? (To 2 s.f in kilometres)

The first thing to recognise is that the terms 'sugar' and 'electrical' are there to confuse you - the substance raised and the type of form of energy used to raise it are not important to the question.
This is ultimately a question of equating energies, Ep as potential energy of the sugar and Ee the electrical energy used to raise it. We know that the gravitational energy of the sugar after raising it will be equal to 1 kWh, so we look to express this in a unit that is more useful, Joules.
1 kWh is the energy output of 1000 Watts of power for 1 hour (6060 seconds). As 1 Watt is 1 Joule / second, we find that:Ee = (1000)(60)(60) = 3,600,000 J
The potential energy of the sugar after raising it to a height h is: E = m
g*h
We have m = 1kg and g = 9.8 m/s/s .
Therefore with Ep = Ee we have:
3,600,000 = (9.81)*hh = 367.3469... km
To 2 s.f this is rounded to: h = 370 km

AL

Related Physics GCSE answers

All answers ▸

Explain what is meant by “terminal velocity” with regards to falling objects.


How do fossil fuel powered power stations and solar powered power stations generates electricity?


What happens to the pressure inside a sealed canister of gaseous oxygen when it is transferred from a cool environment to a warmer environment?


A particle of mass 5kg is acted upon by a force of 400N for a distance of 20m along the x axis. What is its final velocity if it is initally at rest?