How can an Object Come to Rest Without Friction?

How can an object come to rest without friction?
- kartikey (age 14)
Delhi,India

Dear Kartikey,

You bring up an interesting point.  Even Galileo pointed out that once a body is put into motion it will continue so.  The only way to bring a moving body to a standstill is to somehow dissipate its kinetic energy.   One way to do this, as you point out, is with friction.   One can also use electromagnetic tricks if the object has an electrical charge or magnetic properties.

LeeH

Another way, also pointed out by Galileo, is to look at the object differently. Just travel along with it and you'll see it at rest from your viewpoint. You still get to use exactly the same laws of physics from that point of view, so it's just as good a way to look at things as any other. So pushing  yourself (via friction or some normal force or electromagnetically or by gravity)  in the right direction is another way to make that object be "at rest". / Mike W.

(published on 11/05/2013)