Question
A 60 kg student climbs a flight of stairs 4.0 m high in 8.0 s. The student's body converts chemical energy with an efficiency of 25%.
(a) Calculate the useful gravitational potential energy gained. (b) Calculate the useful power output. (c) Calculate the total chemical energy used.
Mark scheme (6 marks):
- (a) GPE = mgh = 60 × 10 × 4.0 (1) = 2400 J (1).
- (b) P = E/t = 2400 / 8.0 (1) = 300 W (1).
- (c) Efficiency = useful/total ⇒ Total = 2400 / 0.25 (1) = 9600 J (1).
- Use g = 10 N/kg (CCEA convention). ECF allowed throughout.
6 marks · take your time before peeking.
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Generated by TopMyGrade AI · cross-check official sources before relying on the mark-scheme phrasing.