# Maximum force that we can exert without breaking the rope?

1. Jan 12, 2010

### NeoPhoenix

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

If we want to pull a block with a weight of 5N attached to a rope that is just able to resist 20N. What is the maximum force that we can exert without breaking the rope? xD

2. Relevant equations

Fnet (in y) = ma = F (applied force) - W (weight)

3. The attempt at a solution

What I think is that: if the rope will just resist 20, and we already know that the weight of the block is 5N, then we should apply a 15N force right ?

2. Jan 12, 2010

### rock.freak667

Re: Forces.

You want the net force to be less than or equal to 20N. Knowing W=5N, what is the applied force you should apply?

3. Jan 12, 2010

### NeoPhoenix

Re: Forces.

actually, this is a problem that I had on a test some days ago...I think that was the question in fact. What force I should apply ?...

4. Jan 12, 2010

### rock.freak667

Re: Forces.

The maximum net force is 20N, using your relevant equation, what would the applied force?

5. Jan 12, 2010

### NeoPhoenix

Re: Forces.

25n ?

6. Jan 12, 2010

### rock.freak667

Re: Forces.

That seems correct.

7. Jan 12, 2010

Re: Forces.

thanks xD