# Newton's First Law

1. Feb 10, 2008

### bonbon49

1. The problem statement, all variables and given/known data
For my A-level homework I have to think whether there are any objects in the universe that move at the same speed in a staight line forever.

2. Relevant equations
I am stuck to think of anything - do any exist?

3. The attempt at a solution

Thanks for the help

2. Feb 10, 2008

### Kurdt

Staff Emeritus
What about something with no mass?

3. Feb 10, 2008

### saiaspire

that would not be possible.. everything in this universe has mass..

however light or any electro magnetic radiation for that matter, in vacuum, moves with the same speed(3x10^8 m/s) forever..

4. Feb 10, 2008

### bonbon49

but objects such as meterorites in the universe change velocity because of mass of nearby planets - is this true?

5. Feb 10, 2008

### HallsofIvy

Staff Emeritus
You titled this "Newton's First Law". Perhaps that has something to do with this problem! What is Newton's first law?

By the way, it is not true that "everything in this universe has mass". In fact, you gave an example in the same post in which you said that. It is, however, true that everything is affected by force.

6. Feb 10, 2008

### Littlepig

But that don't move in a strait line...

or you consider classical mechanics and the speed of light is infinite but move in a strait line, or you consider G.Relativity and light travels at c but don't travel in strait path as there's gravity everywhere. ^_^

EDIT: but for the problem i guess that would be related with 1º law...so, is about direct applying it.