Question
A spaceship is heading directly toward the Earth at a velocity of $0.800c$ . The astronaut on board claims that he can send a canister toward the Earth at $1.20c$ relative to the Earth. (a) Calculate the velocity the canister must have relative to the spaceship. (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?
1. $10c$
2. A velocity of $10c$ is impossibly fast.
3. It's unreasonable to presume a velocity greater than $c$.
Solution Video