Physics - GCSE AQA - Combined Science - Higher: A machine has a useful power output of 900 W and a total power input of 1200 W. In a given time, 72 kJ of energy is transferred to the machine. Calculate the amount of energy usefully transferred by the machine in this time.

Question

A machine has a useful power output of 900 W and a total power input of 1200 W. In a given time, 72 kJ of energy is transferred to the machine. Calculate the amount of energy usefully transferred by the machine in this time.

yxng.edxn · Accepted Answer

Efficiency = useful output / total input
⁹⁰⁰⁄₁₂₀₀ = 0.75

Useful output = total input × efficiency 
0.75 × 72,000 = 54,000 J

72 kJ = 72,000 J

Physics - GCSE AQA - Combined Science - Higher

A machine has a useful power output of 900 W and a total power input of 1200 W. In a given time, 72 kJ of energy is transferred to the machine. Calculate the amount of energy usefully transferred by the machine in this time.

Efficiency = useful output / total input ⁹⁰⁰⁄₁₂₀₀ = 0.75 Useful output = total input × efficiency 0.75 × 72,000 = 54,000 J 72 kJ = 72,000 J

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