The power rating of a vacuum cleaner is 0.8 kW if you use the vacuum cleaner for 2.5 hours how much energy does it use?
First, we need to convert the power rating from kW to watts:
0.8 kW x 1000 = 800 watts
Now, we can calculate the energy used by multiplying the power rating by the time used:
800 watts x 2.5 hours = 2000 watt-hours
Therefore, the vacuum cleaner uses 2000 watt-hours (or 2 kWh) of energy if used for 2.5 hours.