# Newton's Second Law Particle Problem

#### Seraph404

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

While two forces act on it, a particle is to move at the constant velocity v = (3 m/s)i - (4 m/s)j. One of the forces is F1 = (2N)i + (-6N)j. What is the other force?

2. Relevant equations

Fnet = ma

3. The attempt at a solution

Well, I'm really just wanting a hint. I know that the acceleration is zero because the velocity is constant. So how do I use velocity to find the second force? Surely I'm missing something fundamental here. Once again, just a hint would be nice.

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#### PhanthomJay

Homework Helper
Gold Member
1. The problem statement, all variables and given/known data

While two forces act on it, a particle is to move at the constant velocity v = (3 m/s)i - (4 m/s)j. One of the forces is F1 = (2N)i + (-6N)j. What is the other force?

2. Relevant equations

Fnet = ma

3. The attempt at a solution

Well, I'm really just wanting a hint. I know that the acceleration is zero because the velocity is constant. So how do I use velocity to find the second force? Surely I'm missing something fundamental here. Once again, just a hint would be nice.
You pretty much gave yourself a hint when you said that there is no net force. Since one of the two forces are given, what's the other one?

#### Seraph404

You pretty much gave yourself a hint when you said that there is no net force. Since one of the two forces are given, what's the other one?

(-2N)i + (6N)j ?

#### PhanthomJay

Homework Helper
Gold Member
(-2N)i + (6N)j ?
Correct! (the answer would be the same regardless of the value of the constant velocity).

Oh okay! Thanks!

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