Grade 11 · Science · Physics

11th grade The speed of light and relativity worksheet

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The speed of light and relativity

Grade 11 Science Worksheet - Building Confidence

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Circle the best answer, or write your answer on the line.

A particle moves at 0.8c. Using γ = 1 ÷ √(1 − v²/c²), what is γ, to 0.01, Bo?
Read this first
Photon diagram with two observers
Observer A rides a train moving at 0.6c, holding a light clock where light bounces between two mirrors. Observer B stands beside the track. Both measure the light's speed as c. B sees the light take a longer, slanted path, so B sees A's clock tick slower.
2.
In the photon diagram, what speed does B measure for the light in A's clock, Jun?
- c − 0.6c
- c, the same as A measures
- c + 0.6c, adding the train's speed
3.
In the photon diagram, whose clock does B see ticking slower, Kira?
- Both tick at the same rate
- A's clock on the train
- B's own clock
4.
In the photon diagram, why does B see each tick take longer, Luz?
- The light slows down
- The light's path is longer
- B's eyes see light more slowly
5.
What is the speed of light in a vacuum, Milo?
- 299,792,458 m/s
- 150,000 m/s
- 3,000,000,000 m/s
6.
A train's headlight shines forward as it moves. How fast does the light leave, measured from the ground, Noah?
- c, the same as from a still lamp
- c minus the train's speed
- c plus the moving train's own speed
7.
Which statement about light's speed in a vacuum is true, Pia?
- It is faster for brighter light
- It depends on how fast the source moves
- It is the same for every observer
8.
What does special relativity say about time, Ren?
- Time runs alike in each frame
- Time stops on trains
- Moving clocks run slow
9.
Why don't we notice time slowing on a moving bus, Tala?
- Buses are too heavy for it
- Its speed is tiny compared with c
- The bus's air slows the effect down
10.
Can a rocket ever reach the speed of light, Zee?
- Yes, if it speeds up for years
- No: nothing with mass can
- Yes, with a big enough engine

11th grade The speed of light and relativity worksheet – printable — Print: 1 2 3 4 5 6

About this worksheet

The speed of light and relativity. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

I can say that every observer measures the same speed for light, c = 299,792,458 m/s, and that nothing with mass reaches it.
I can find γ = 1 ÷ √(1 − v²/c²) and use t = γt₀: a moving clock runs slow, and a moving object is shorter along its motion.
I can explain why fast muons from high in the air reach the ground.
I can read GPS clock effects: weaker gravity makes satellite clocks gain 45.7 μs a day, their speed makes them lose 7.1 μs, and the net is +38.6 μs.

Standard: none (FL)

Words to know

frame of reference: The point of view, moving or still, that measurements are made from

time dilation: A moving clock measured as ticking slower

length contraction: A moving object measured as shorter along its motion

γ (gamma): 1 ÷ √(1 − v²/c²); 1 at rest, larger near c

muon: A heavier cousin of the electron that decays in about 2.2 μs

Common mistakes

Your child left out the square root. γ = 1 ÷ √(1 − v²/c²).

Your child divided by γ. A moving clock runs slow, so its lifetime looks longer: t = γt₀.

Your child used the muon's rest lifetime. From the ground, its lifetime is stretched by γ, so it travels farther.

Questions parents ask

What is the most common mistake with the speed of light and relativity?

Your child left out the square root. γ = 1 ÷ √(1 − v²/c²).

Are these 11th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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