An astronaut is floating in space when the support line is cut. if the 68kg astronaut needs to reach the spaceship (20m away), how long will it take if he throws a 12kg canister at 12m/s?

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.

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.