You have been hired to check the technical correctness of an upcoming made-for-T

Question

You have been hired to check the technical correctness of an upcoming made-for-TV murder mystery that takes place in the space station. In one scene, while Sally is on a spacewalk the villain cuts her safety line, intending that she will be stuck outside the station. When the safety line is cut, Sally is 200 meters from the station’s air lock and not moving with respect to it. She has only 5 minutes left in her space suit. Being familiar with physics, Sally decides to try to use conservation of momentum to get back to the station. She unstraps a 10-kg tool kit and throws it with a speed of 8 m/s in the direction opposite to the space station. In the script, Sally, who has a mass of 100 kg without the toolkit, survives, but is this correct? Find the momentum of Sally after she throws the toolkit and from that her velocity and from that the time it would take her to get back to the space station.

Explanation / Answer

momentum of sally before throwing Pi = 0

momentum of sally after throwing Pf = Ms*Vs + Mkit*Vkit

from momentum conservation

Pi = Pf

Ms*Vs + Mkit*Vkit = 0

Vkit = -8 m/s

Mkit = 10 kg

Ms = 100 kg

Vs = ?

100*Vs - 10*8 = 0

speed of sally vs = 0.8 m/s

time taken to travell 200 m = 200/0.8 = 250 seconds = 250/60 minutes = 4.2 minutes

sally survives

this is correct

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