O-LevelPhysicsForces5054/21 · May/June 2021 · Q17 Marks

An aircraft flies at a constant height. Air drag and the force from the aircraft's engines together produce a force on the aircraft of 36 kN due north, as shown in Fig. 1.1. The wind produces a force of 12kN towards the east. [Figure 1.1]

(a)Draw a scale drawing to show the resultant force acting on the aircraft. Use your drawing to determine the size of the resultant force and the angle between the resultant force and north. size of resultant force = angle =[3]
(b)(i)Describe how a uniform acceleration differs from a non-uniform acceleration.[2]
(b)(ii)The mass of the aircraft is 60000kg. Calculate the acceleration of the aircraft. acceleration =[2]

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Mark scheme

Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.

[B1] scale vector diagram showing 12 N, 36 N and correct resultant force in correct direction
[B1] 38 ± 1 kN
[B1] 018 ± 3°
[B1] (only in uniform acceleration) same increase / change in speed/ velocity or has a constant acceleration or speed-time graph is a straight line
[B1] (only in uniform acceleration) same increase / change in speed/ velocity in same time (period) or same rate of change of speed / velocity (with time) or change in speed / velocity is proportional to time
[C1] (a =) F/ m in any way, algebraic or numerical
[A1] 0.63-0.66 m/s²

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