# Negative or positive of a displacement and velocity

1. Jul 9, 2007

### MIA6

I think when we talk about negative or positive of a displacement, we mean that the direction of this displacement which is either going downward or upward. But my question is how about when it says +/-velocity. Does it mean the direction or it means it speeds up or slows down? I think velocity is influenced by displacement according to the formula? so it must be influenced by the sign (+/-) of a displacement. Same happens to acceleration? +/- a. How can i know they mean the direction or speeds.

Thanks a lot.

2. Jul 9, 2007

### G01

The sign of a velocity is dependent on it's direction. A negative velocity means that the object is moving opposite to the direction we call positive. A negative acceleration also follows the same argument. Be careful with acceleration. A negative acceleration does not necessarily mean that an object is slowing down. All it means is that the acceleration points in the negative direction.

Did this help?

3. Jul 10, 2007

### MIA6

yes, it helps. thank you.