Efficiency Calculation Worksheet
BTEC Applied Science Unit 1: Efficiency Worksheet Name____________
efficiency = ( 100 %)
1 What is the efficiency of a motor that turns 100 J of electrical energy into 70 J of useful kinetic energy? Give your answer as a decimal.
2 An electric winch is used to lift a load of mass 2 kg a height of 1.5 m. It uses 50 J of energy when it does this.
i) Calculate the amount of potential energy gained by the load using the formula:
Ep = mgh where
Ep is the potential energy gained m is the mass of the load in kg g is the acceleration due to gravity (9.8 ms-2) h is the vertical distance moved by the load
ii) Now calculate the efficiency of the winch.
3 Solar cells are used to provide electrical energy for a water pump that pumps water into a tank from a river.
The energy wasted as water moves along the pipes is very small and can be ignored.
Solar energy (light energy) of 1000 J hits the solar cell. efficiency = ( 100 %)
a The efficiency of the solar cell is 0.20 (20%). Calculate the amount of electrical energy produced by the solar cell.
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b The electrical energy you calculated in a passes to the water pump. The efficiency of the water pump is 0.80 (80%). Calculate the amount of output energy produced by the pump.
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c i Use your answer to b to calculate the overall efficiency of the whole system in converting solar energy into gravitational potential energy of water in the tank.
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d Draw a Sankey diagram below to show what happens to the solar energy that hits the solar cell.
efficiency = ( 100 %)
1 What is the efficiency of a motor that turns 100 J of electrical energy into 70 J of useful kinetic energy? Give your answer as a decimal.
2 An electric winch is used to lift a load of mass 2 kg a height of 1.5 m. It uses 50 J of energy when it does this.
i) Calculate the amount of potential energy gained by the load using the formula:
Ep = mgh where
Ep is the potential energy gained m is the mass of the load in kg g is the acceleration due to gravity (9.8 ms-2) h is the vertical distance moved by the load
ii) Now calculate the efficiency of the winch.
3 Solar cells are used to provide electrical energy for a water pump that pumps water into a tank from a river.
The energy wasted as water moves along the pipes is very small and can be ignored.
Solar energy (light energy) of 1000 J hits the solar cell. efficiency = ( 100 %)
a The efficiency of the solar cell is 0.20 (20%). Calculate the amount of electrical energy produced by the solar cell.
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b The electrical energy you calculated in a passes to the water pump. The efficiency of the water pump is 0.80 (80%). Calculate the amount of output energy produced by the pump.
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c i Use your answer to b to calculate the overall efficiency of the whole system in converting solar energy into gravitational potential energy of water in the tank.
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d Draw a Sankey diagram below to show what happens to the solar energy that hits the solar cell.