Conceptual question on momentum

[Bob Loblaw]

Homework Statement

An astronaut is on a space walk when his tether breaks. He has no rocket pack, only a big wrench. How does he get back to the ship?

Homework Equations

p=mv

The Attempt at a Solution

I have no idea. I imagined him using the wrench as some sort of "paddle" as he space-canoed his way back to the ship. Any more realistic ideas?

 

[learningphysics]

Think conservation of linear momentum. paddle won't work because there's only empty space there... nothing to push against.

 

[ogb p]

As a scientist, the first thing to consider in this scenario is the conservation of momentum. The astronaut's momentum will remain constant unless acted upon by an external force. Since he has no rocket pack, he will have to use the wrench to create an external force that will change his momentum. One possible solution could be for the astronaut to throw the wrench in the opposite direction of the ship with a certain force. This would result in a change in his momentum in the opposite direction, propelling him towards the ship. Another solution could be for the astronaut to use the wrench to push off of a nearby object, such as a floating debris, to change his momentum and propel himself towards the ship. Ultimately, the key is to use the wrench to create a force that will change the astronaut's momentum and bring him closer to the ship.