The speed of light and relativity
Grade 11 Science Worksheet - Building Confidence
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?
A particle moves at 0.96c. Using γ = 1 ÷ √(1 − v²/c²), what is γ, to 0.01, Esme?
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.
In the photon diagram, what speed does B measure for the light in A's clock, Jun?
- c + 0.6c, adding the train's speed
- c, the same as A measures
- c − 0.6c
In the photon diagram, whose clock does B see ticking slower, Kira?
- Both tick at the same rate
- B's own clock
- A's clock on the train
In the photon diagram, why does B see each tick take longer, Luz?
- The light slows down
- B's eyes see light more slowly
- The light's path is longer
What is the speed of light in a vacuum, Milo?
- 3,000,000,000 m/s
- 150,000 m/s
- 299,792,458 m/s
A train's headlight shines forward as it moves. How fast does the light leave, measured from the ground, Noah?
- c minus the train's speed
- c, the same as from a still lamp
- c plus the moving train's own speed
Which statement about light's speed in a vacuum is true, Pia?
- It is the same for every observer
- It is faster for brighter light
- It depends on how fast the source moves
Why don't we notice time slowing on a moving bus, Tala?
- Its speed is tiny compared with c
- The bus's air slows the effect down
- Buses are too heavy for it
Can a rocket ever reach the speed of light, Zee?
- Yes, with a big enough engine
- No: nothing with mass can
- Yes, if it speeds up for years