Einstein’s first postulate of special relativity asserts that the laws of physics are identical in all inertial reference frames.
State the second postulate of special relativity and explain how it is consistent with the equation for the speed of electromagnetic waves in a vacuum:
c=1μ0ε0 c = \frac{1}{\sqrt{\mu_0 \varepsilon_0}} c=μ0ε01An unstable neutral pion is produced at point P in a high-energy physics experiment and travels at a constant velocity towards a particle detector located at point Q. The distance PQ in the frame of reference of the pion is measured to be 18 m18 \text{ m}18 m. An observer in the laboratory frame (where the detector is at rest) measures the pion's speed to be 1.8×108 m s−11.8 \times 10^8 \text{ m s}^{-1}1.8×108 m s−1. The rest mass of a neutral pion is 2.40×10−28 kg2.40 \times 10^{-28} \text{ kg}2.40×10−28 kg.
Calculate the distance PQ in the frame of reference of the detector.
Show that the kinetic energy EkE_{\mathrm{k}}Ek of the pion is about 5.4×10−12 J5.4 \times 10^{-12} \text{ J}5.4×10−12 J.
Sketch the variation of EkE_{\mathrm{k}}Ek with speed vvv for the pion. Your sketch should show both the classical prediction Ek=12m0v2E_{\mathrm{k}} = \frac{1}{2}m_0v^2Ek=21m0v2 (as a dashed line) and the relativistic curve (as a solid line) for speeds up to the speed of light c=3.0×108 m s−1c = 3.0 \times 10^8 \text{ m s}^{-1}c=3.0×108 m s−1. Identify the key differences between the curves.
22 exam-style questions on AQA A Level Physics Special relativity (A-level only), covering The Michelson-Morley experiment (A-level only), Einstein's theory of special relativity (A-level only), Time dilation (A-level only), Length contraction (A-level only), and Mass and energy (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.