Physics · Oct / Nov 2021 · Paper 41 · Question 4
0625
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The question as text
A train of mass 1.8 × 105 kg is at rest in a station. At time t = 0, the train begins to accelerate along a straight, horizontal track and reaches a speed of 20 m / s at t = 15 s. The train continues at a speed of 20 m / s for 10 s. At t = 25 s, the driver applies the brakes and the resistive force on the train causes it to decelerate uniformly to rest in a further 24 s. Fig. 4.1 is an incomplete distance–time graph for this journey. 0 10 20 30 40 50 0 200 400 600 t / s distance / m Fig. 4.1
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4(a)(i)[1]
straight line begins at (15 s, 120 m) and continues to end of given line
4(a)(ii)[1]
curve with increasing gradient from origin to beginning of candidate’s (a)(i)
4(b)[3]
(Ek =) ½mv2 in any form
½ × 1.8 × 105 × 202
3.6 × 107 J
4(c)(i)[2]
(work done =) force × distance (moved in the direction of the force)
(work done =) force × distance moved in the direction of the force
4(c)(ii)[1]
240 m c.a.o.
4(c)(iii)[2]
3.6 × 107 / 240 or kinetic energy / distance or (a =) 20 / 24 or ∆v / t in any form or 0.83 or (F =) ma in any form
1.5 × 105 N
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