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 ▸

How do we know about the structure of the atom?


A 1000kg car accelerates from 0 to 20 m/s in 15 seconds. Calculate the acceleration of the car, the force required for this acceleration and the momentum of the car at 20 m/s.


which part of the electromagnetic spectrum provides most of the energy to heat the water in a solar thermal power station?, how does this heated water allow electricity to be generated?


A car travelling at 14 m/s has to make an emergency stop so applies the brakes and it takes 1.5s to become stationary. What distance has the van travelled in that time?