A petrol engine has a total input of 80000W and a useful output of 28000W. What is the efficiency of the engine as a decimal?
A bike uses 20J of energy, 2J are wasted in sound, 18J turn into kinetic energy. What is the efficiency of the bike as a percentage?
If an electric oven is 70% efficient, what does this mean?
A kettle uses 63J of energy and it produces 58J of heat, what is the efficiency of the kettle in a decimal?
What is the efficiency of a phone if it uses 31J and wastes 19J of energy as a percentage?
How much energy does a toaster use if the efficiency is 0.40 and it produces 30J of heat energy?
An electric fan has a useful output of 200J and an efficiency of 8%, what is the total input of the fan?
A speaker gives out 80J of sound energy. Calculate the total input energy if its efficiency is 0.35.
A drill has an efficiency rating of 65% and uses 250W of energy, how much of the energy is useful?
A vacuum uses 150J of energy, 10J is wated in sound, what is the efficiency of the vacuum.
How much energy does a mixer use if the efficiency is 48% and it wastes 20J of energy?
A gas boiler has a total output of 13000W and an efficiency of 0.9%, what is the useful output power of the boiler?
A TV has an efficiency of 86%. If the input power is 2600W, calculate the useful output power.
A speaker gives out 200J of sound energy. Calculate the total input energy if its efficiency is 78%.
A motor has an efficiency of 45%. if the input power is 32000W, calculate the useful output power.