10 IB Physics Option A questions you should know

Many teachers will tell you that the key to keeping your IB studies on track is to review material you have covered regularly in manageable chunks. Breaking your study and revision process down incrementally can help you retain the knowledge you are acquiring and avoid last minute exam cramming, which is an ineffective method to achieving exam success.

To help you along the way, we’ve pulled together 10 IB Physics Option A questions and answers for Relativity that will help you review essential material. If you find the questions helpful, be sure to check out our Physics Option A: Relativity Standard and Higher Level study guide by Hugh Duncan. The questions in this article have been extracted from this book and there are plenty more in it to keep your IB Physics Option A practice going – 40+ questions, 20+ worked examples, and hands-on tasks to practice your labelling and graphing skills!

10 IB Physics Option A Relativity Questions for Standard Level & Higher Level Students

Introduction to relativity

1. What is a Galilean transformation?

2. Duncewind is being silly on a moving sidewalk. The sidewalk is moving 4.0 ms^-1 to the right relative to the ground, while he is walking 2.0ms^-1 to the left relative to the sidewalk. What is his velocity relative to the ground?

Lorenz Transformation

3. Syborg is standing in the middle of a spacecraft that is 6.0 x 10⁸ m long. He sees the candle at each end stop burning at the same instant. After how much time does Syborg see the flames die? His friend Sebby is watching from a space station as he passes by at 2.0 x 108 ms^-1. At what times will Sebby say the final light from each candle set out?
4. Zaphod leaves his birthday part, which is on an orbiting space station travelling at 0.90c and uses a transporter beam to the surface of the planet below (which is not spinning). According to his watch it takes him exactly one year to get ready for his next birthday party. When he beams back aboard, how much time will have passed on the station?

Space-time Diagrams

5. Out of a set of triplets, Hughie stays on earth, Dewey flies off in a spacecraft at a high speed northwards, while Louie does the same but southwards. The two travelling triplets return to earth after some time. How do their ages compare?
6. Duncewind does an unusual experiment. He has 100g of a radioactive isotope relativium with half-life of 25yrs and splits it into two equal samples. One he keeps to pass on to his granddaughter Jazzwind while the other he puts in a spaceship and sends it off at 0.87c. The craft returns 50 yrs later, according to little Miss Duncewind when she collects the second relativium. How much will remain from each sample?

Relativistic mechanisms

7. Under what conditions can an object with a rest mass reach the speed of light?
8. A proton in a particle accelerator is moved through a voltage of 120MV. What is the final velocity?

General relativity

9. A photon of a certain wavelength is sent down a mineshaft, reflected from a mirror and back to the same height. How does the new wavelength compare to the original?
10. It is believed that there is a black hole at the centre of the Milky Way galaxy with a mass of 100 million suns. What would be the Schwarzschild radius?

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Answers to the Physics Option A Standard & Higher Level Questions

1. The relationship between frames in non-relativistic motion.
2. 2.0ms^-1 to the right.
3. 1.0s from both ends for Syborg, 3.0s from the back, 0.6s from the front for Sebby.
4. 0.44y
5. Hughie will have aged the most as he didn’t travel while both Dewie and Louie will age equally less as they have made identical journeys.
6. On earth the 50g of isotope will have experienced 50yrs of time which is two half-lives so will reduce to a quarter, i.e. 12.5g. Meanwhile the travelling sample will only experience 25yrs passing which is one half-life so there will be 25g remaining.
7. None.
8. qV = 120MeV so E^k + E⁰ = 120 + 938 = 1058MeVc^-2 = 1.13 so v = 0.46c
9. It must be the same. Any energy gained in falling is lost in rising.
10. 3.0 x 10¹¹ or about twice the earth’s orbital radius.

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Keep Revising

The above questions are just a sample of the range of questions you will need to be practicing for your IB Physics Option A Relativity exam. Start practicing early and do it often so that the skills and techniques required to successfully answer questions become second nature.

Your school will have provided you with a number of great resources to help you along the way, including your IB Physics data booklet which contains all the equations you need to know. If you’re looking for a bit more support for IB Physics Option A, checkout our article on Common Exam Mistakes to Avoid or visit our IB Physics subject page for more articles and tools.