# Homework Help: Effect of a net force of zero mechanics question

1. Jan 24, 2014

### Tiven white

1. The problem statement, all variables and given/known data
True or false

If an object originally at rest is subjected to more than one non zero force but the forces sum to zero then the particle will not move.

2. Relevant equations
None

3. The attempt at a solution
I say false I think it something to do with angular acceleration not sure though
Other solutions would be appreciates

2. Jan 24, 2014

### Simon Bridge

What is Newton's 1st law?
(Write it out completely.)

You mentioned the possibility of rotation...
Can a linear force cause rotation in a particle?

3. Jan 24, 2014

### Tiven white

New tons first law states that if the net force on an object is zero the object moves with cconstant velocity. Alternately an object at rest stays at rest or if moving moves with constant velocity unless acted on by aN unbalanced force

4. Jan 24, 2014

### Tiven white

So what's ur solution to the problem

5. Jan 24, 2014

### Simon Bridge

Compare with post #1.

Is the object at rest or moving at a constant velocity?
Is it acted on by an unbalanced force?

6. Jan 25, 2014

### Tiven white

I think the answer is true due to the reconsideration. After post.three regarding newtons first.law

7. Jan 25, 2014

### Tiven white

Is it true?

8. Jan 25, 2014

### Staff: Mentor

Yes. (Assuming that rotation is off the table. And even if it was a rotatable object, its center of mass would not move.)

9. Jan 25, 2014

### Tiven white

The reason why I had initially.said false was because there was some distinction being made from an object and a particle in mechanics so an object could receive rotation since the forces acting on it could be at different points while for a particle ths re can be no rotation since the force is applied at.the same pointe due to its size. So I had a problem figuring
Whether the question was structured for an 'object' or a particle but both terms are used synonymously in the question.

10. Jan 25, 2014

### Simon Bridge

Yep - I would say there is a small ambiguity concerning what is meant by "movement" that can only be cleared up by context.

We could have argued, for eg, that the object will have a temperature, and therefore it's component atoms are moving: if an object jiggles about at random, is it "moving"? But then, you are told that it is initially "at rest" - if it jiggles about, is it also "at rest"? In normal English usage it is possible to describe something as jiggling about while staying in the same place... but is that the same thing?

We are told first that it is "an object" and then that it is "the particle" ... which is it?

This kind of judgement call is quite common.
Balance of probability is that the object continues in a state of rest - the mention of "the particle" and "at rest" (both being special-use terms in physics) being the clincher.