IB Physics HL A.5.6 Lorentz transformations Question Bank

Practise IB Physics HL A.5.6 by applying lorentz transformations concepts to exam-style physics questions.

Exam points

identify the relevant physical quantity, model or diagram
apply the correct equation and units to the evidence
justify the result using conservation laws, forces or energy relationships

[Maximum number: 1]

An observer P sitting in a train moving at a speed v measures that his journey takes a time $\Delta t_{\mathrm{p}}$ . An observer Q at rest with respect to the ground measures that the journey takes a time $\Delta t_{\mathrm{Q}}$ .

According to Q there is an instant at which the train is completely within the tunnel. At that instant two lights at the front and the back of the train are turned on simultaneously according to Q .

Figure for Question A.5.6 (HL)—Lorentz transformations question 1 — IB Physics HL

The spacetime diagram according to observer Q shows event B (back light turns on) and event F (front light turns on).

Apply a Lorentz transformation to show that the time difference between events B and F according to observer P is $2.5 \times 10^{-7} \mathrm{~s}$ .

$\begin{aligned} \Delta t^{\prime}=1.25 \times \frac{0.6 \times 100}{3 \times 10^{8}} <2.5 \times 10^{-7} \mathrm{~S}> \end{aligned}$

Allow ECF for gamma from (c).

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A.5.6 (HL)—Lorentz transformations question 1