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Question 18M.3.SL.TZ2.3

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Date May 2018 Marks available [Maximum mark: 4] Reference code 18M.3.SL.TZ2.3
Level SL Paper 3 Time zone TZ2
Command term Calculate, Outline Question number 3 Adapted from N/A
3.
[Maximum mark: 4]
18M.3.SL.TZ2.3

Rocket A and rocket B are travelling in opposite directions from the Earth along the same straight line.

M18/4/PHYSI/SP3/ENG/TZ2/03

In the reference frame of the Earth, the speed of rocket A is 0.75c and the speed of rocket B is 0.50c.

(a.i)

Calculate, for the reference frame of rocket A, the speed of rocket B according to the Galilean transformation.

[1]

Markscheme

1.25c

[1 mark]

(a.ii)

Calculate, for the reference frame of rocket A, the speed of rocket B according to the Lorentz transformation.

[2]

Markscheme

ALTERNATIVE 1

u ′ = ( 0.50 + 0.75 ) 1 + 0.5 × 0.75 c

0.91c

ALTERNATIVE 2

u ′ = − 0.50 − 0.75 1 − ( − 0.5 × 0.75 ) c

–0.91c

 

[2 marks]

(b)

Outline, with reference to special relativity, which of your calculations in (a) is more likely to be valid.

[1]

Markscheme

nothing can travel faster than the speed of light (therefore (a)(ii) is the valid answer)

 

OWTTE

[1 mark]

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