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Question 19N.3.SL.TZ0.b(iv)

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Date November 2019 Marks available [Maximum mark: 2] Reference code 19N.3.SL.TZ0.b(iv)
Level SL Paper 3 Time zone TZ0
Command term Calculate Question number b(iv) Adapted from N/A
b(iv).
[Maximum mark: 2]
19N.3.SL.TZ0.b(iv)

A long straight current-carrying wire is at rest in a laboratory. A negatively-charged particle P outside the wire moves parallel to the current with constant velocity v relative to the laboratory.

In the reference frame of the laboratory the particle P experiences a repulsive force away from the wire.

The velocity of P is 0.30c relative to the laboratory. A second particle Q moves at a velocity of 0.80c relative to the laboratory.

Calculate the speed of Q relative to P.

[2]

Markscheme

u'=0.80+0.301+0.80×0.30c ✔

=0.89c ✔

NOTE: Accept 0.89c if all negative values used. Accept –0.89c even though speed is required.

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