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Question 18M.3.SL.TZ1.d

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.SL.TZ1.d
Level SL Paper 3 Time zone TZ1
Command term Calculate Question number d Adapted from N/A
d.
[Maximum mark: 2]
18M.3.SL.TZ1.d

An observer on Earth watches rocket A travel away from Earth at a speed of 0.80c. The spacetime diagram shows the worldline of rocket A in the frame of reference of the Earth observer who is at rest at x = 0.

Another rocket, B, departs from the same location as A but later than A at ct = 1.2 km according to the Earth observer. Rocket B travels at a constant speed of 0.60c in the opposite direction to A according to the Earth observer.

Calculate the velocity of rocket B relative to rocket A.

[2]

Markscheme

u ′ = − 0.6 − 0.8 1 − ( − 0.6 ) × 0.8

= «–»0.95 «c»

[2 marks]

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