Question

An astronaut with a mass of `85 kg` is floating in space. If the astronaut throws an object with a mass of `20 kg` at a speed of `5/8 m/s`, how much will his speed change by?

Answer 1

`0.15m/s` `backward`

Explanation:

This can be solved using the law of conservation of momentum. The formula is:

`M_1V_1 + M_2V_2=M_1V_1' + M_2V_2'`)

Given:

`M_1=85kg`
`V_1=0 m/s` (at rest)
`M_2=20kg`
`V_2=0 m/s`(at rest)
`V_2'=5/8 m/s`

Required: `V_1'= ?`

Solution:

1. Use the formula reflected above and plug in data provided in the problem.

2.Initial speeds of the astronaut and the object are zeros since both are at rest.

3.Just remember that momentum is being conserved after throwing the object `5/8 m/s` to the space.

Answer:

`-0.15 m/s` or `0.15 m/s backward`