Question

1. An astronaut with a mass of 77.5kg is stuck in space floating 15.0m away from his ship.
His motion relative to the ship is 0 m/s. Fortunately, he is holding a 2.0kg wrench. He throws
the wrench in the opposite direction of the ship at 12m/s. What is the wrench's change in
momentum?

Answer 1

Answer:

24 kg m/s

Explanation:

The change in momentum of the wrench is given by:

$\Delta p = p_f - p_i$

where

$p_f$ is its final momentum

$p_i$ is its initial momentum

At the beginning, the wrench is at rest together with the astronaut, so its momentum is zero:

$p_i = 0$

After it is launched, its momentum becomes

$p_f = m v$

where

m = 2.0 kg is its mass

v = 12 m/s is its velocity (taking the direction of the wrench motion as positive)

Substituting,

$p_f = (2.0)(12)=24.0 kg m/s$

So, the wrench's change in momentum is

$\Delta p = p_f - p_i = 24-0=24 kg m/s$