IB Physics HL A.5.15 Muon decay evidence Question Bank

Practise IB Physics HL A.5.15 by applying muon decay evidence 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: 3]

This question is about time dilation and relativistic mass.

Muons are produced in the upper atmosphere of Earth and travel towards the surface of Earth where they are detected. Explain how, with reference to the situation described in (b), the production and detection of muons provide evidence for time dilation.

the muons are equivalent to S and the Earth to X, Y;
without time dilation most muons would decay before reaching the Earth's surface;
from Earth frame, with time dilation, the (proper) half-life of muons becomes dilated/larger;
$\left.\begin{array}{l}\text { from muon frame, with time dilation, the (proper) } \\ \text { journey time is less than that on Earth; }\end{array}\right\} \begin{aligned} & \text { (do not award marking point } \\ & \text { for arguments just based on } \\ & \text { length contraction) }\end{aligned}$ $\left.\begin{array}{l}\text { fewer muons decay/more muons survive than } \\ \text { expected without time dilation; }\end{array}\right\} \begin{aligned} & \text { (award marking point even if } \\ & \text { no explanation is given) }\end{aligned}$

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A.5.15 (HL)—Muon decay evidence question 1