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IB Physics HL A.5 Galilean and Special Relativity Question Bank

Practise IB Physics HL A.5 by applying frame transformations, invariant intervals, spacetime diagrams and experimental evidence for relativity.

Syllabus
First assessment 2025
Course
Physics HL
Level
HL

Exam points

  • apply Galilean and relativistic transformations to relate coordinates and velocities between inertial frames
  • use the Lorentz factor, invariant space-time interval, proper time and proper length in relativity calculations
  • interpret space-time diagrams, time dilation, length contraction and muon-decay evidence

Covered syllabus points

A.5.1 (HL)—Reference framesA.5.2 (HL)—Galilean relativityA.5.3 (HL)—Galilean transformationsA.5.4 (HL)—Galilean velocity additionA.5.5 (HL)—Two postulates of special relativityA.5.6 (HL)—Lorentz transformationsA.5.7 (HL)—Relativistic velocity additionA.5.8 (HL)—Space-time intervalA.5.9 (HL)—Proper time interval and proper lengthA.5.10 (HL)—Time dilationA.5.11 (HL)—Length contractionA.5.12 (HL)—Relativity of simultaneityA.5.13 (HL)—Space-time diagramsA.5.14 (HL)—World lines and speedA.5.15 (HL)—Muon decay evidence

A.5 Galilean and special relativity question 1

[Maximum number: 13]

This question is about time dilation and relativistic mass.

Question (a)

(a)

Two space stations X and Y are at rest relative to each other. The separation of X and Y as measured in their frame of reference is 1.80×1011 m1.80 \times 10^{11} \mathrm{~m}.

Figure for Question (a) — IB Physics HL

State what is meant by a frame of reference.

[ 1 ]

Question (b)

(b)

A radio signal is sent to both space stations in (a) from a point midway between them. On receipt of the signal a clock in X and a clock in Y are each set to read zero. A spaceship S travels between X and Y at a speed of 0.750 c as measured by X and Y . In the frame of reference of S , station X passes S at the instant that X 's clock is set to zero. A clock in S is also set to zero at this instant.

[ 9 ]

Question (i)

(i)

Calculate the time interval, as measured by the clock in X , that it takes S to travel from X to Y .

[ 2 ]

Question (ii)

(ii)

Calculate the time interval, as measured by the clock in S , that it takes S to travel from X to Y .

[ 2 ]

Question (iii)

(iii)

Explain whether the clock in X or the clock in S measures the proper time.

[ 2 ]

Question (iv)

(iv)

Explain why, according to S , the setting of the clock in X and the setting of the clock in Y does not occur simultaneously.

[ 3 ]

Question (c)

(c)

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.

[ 3 ]

A.5 Galilean and special relativity question 2

[Maximum number: 1]

State a postulate that is the same for both special relativity and Galilean relativity.

A.5 Galilean and special relativity question 3

[Maximum number: 7]

This question is about the Michelson-Morley experiment.

The diagram shows the basic features of the Michelson-Morley experiment.

Figure for Question A.5 Galilean and special relativity question 3 — IB Physics HL

Question (a)

(a)

During the experiment, Michelson and Morley slowly rotated the apparatus through 90∘90^{\circ}. Discuss, with reference to Galilean transformations, the changes that Michelson and Morley expected to observe during the experiment.

[ 4 ]

Question (b)

(b)

Describe how the observations made by Michelson and Morley differed from what was expected.

[ 1 ]

Question (c)

(c)

c) Explain the importance of the outcome of the Michelson-Morley experiment in support of the special theory of relativity.

[ 2 ]
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