Answer: 9.43 s
Explanation:
Since there is no external force acting in space, the total momentum of the entire system would be conserved.
When the astronaut throws a canister, an equal and opposite amount of force would act on the astronaut which means momentum of the canister would be equal to momentum of the astronaut,
⇒ m v = m' v'
⇒ 12 kg × 12 m/s = 68 kg × v'
The velocity of the astronaut would be:
v' = 2.12 m/s
The distance need to be covered by astronaut to reach the spaceship = 20 m
Time taken : Distance/ velocity = 20 m / 2.12 m/s = 9.43 s.
Hence, astronaut would take 9.43 s to reach the spaceship.
