Available practice: 71 of 75 marks. Parts 5(a)(ii), 5(b)(i), 11(a) await marking support. Scores cover available parts only. Theory Paper 2: Section A is compulsory and Section B offers a choice of two questions. Four published mark-scheme discrepancies across the two variants are held from automatic marking.
(a)Fig. 2.1 shows an electric motor lifting a load. The load, of weight 5.0 N, is raised through a vertical height of 3.5 m at a constant speed. The efficiency of the electric motor is 0.65 (65%). Calculate the increase in gravitational potential energy of the load.
Answer guidance
Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.
[2 marks]
(b)(i)Fig. 2.1 shows an electric motor lifting a load. The load, of weight 5.0 N, is raised through a vertical height of 3.5 m at a constant speed. The efficiency of the electric motor is 0.65 (65%). State the formula that relates efficiency, energy input and useful energy output.
Answer guidance
State A short answer. No explanation is needed, and adding one cannot earn extra marks.
[1 mark]
(b)(ii)Fig. 2.1 shows an electric motor lifting a load. The load, of weight 5.0 N, is raised through a vertical height of 3.5 m at a constant speed. The efficiency of the electric motor is 0.65 (65%). Calculate the energy input to the motor.
Answer guidance
Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.
[2 marks]
(c)Fig. 2.1 shows an electric motor lifting a load. The load, of weight 5.0 N, is raised through a vertical height of 3.5 m at a constant speed. The efficiency of the electric motor is 0.65 (65%). Suggest one reason why the efficiency of the motor is less than 1.0 (100%).
Answer guidance
Suggest More than one answer may be acceptable, so long as it is consistent with the physics.
[1 mark]
5054/22/M/J/16Cambridge O Level Physics 5054 · May/June 2016 · Paper 2 variant 2 · Question 2