# Homework Help: Velocity formula

1. Oct 17, 2004

### Katie

velocity formula....

could anyone tell me the formula for velocity?
and acceleration?

thanks,
Katie

2. Oct 17, 2004

### arildno

What do you mean??
If x(t) is a particle's position at time "t", then the velocity of the particle, v(t), is given by:
$$v(t)=\frac{dx}{dt}$$
That is, the velocity of the object is the rate of change of the position.

Similarly, acceleration, a(t) is the rate of change of velocity, that is:
$$a(t)=\frac{dv}{dt}=\frac{d^{2}x}{dt^{2}}$$

3. Oct 17, 2004

### Dooga Blackrazor

Acceleration = (Initial Velocity x Final Velocity) divided by time, or
a = (vf-vi) divided by t

Velocity = d/t or distance divided time.

However since velocity is a vector quantity (meaning it has magnitude(size), and direction) the d/t doesn't provide you with direction. Depending on the level of physics your doing, you might not be required to have a direction with velocity.

4. Oct 17, 2004

### nolachrymose

Velocity is equal to displacement (a vector, as opposed to distance, a scalar) over time. Speed is equal to distance over time.

5. Oct 17, 2004

### Tom McCurdy

$$\Delta=$$change in

Formula for Average Velocity and Acceleration

<Velocity> = $$\frac{\Delta distance}{\Delta time}$$

<Acceleration> = $${\frac {\Delta Velocity}{\Delta time}}$$

Last edited: Oct 17, 2004
6. Oct 17, 2004

### robphy

Change "velocity" to "average-velocity".
Change "acceleration" to "average-acceleration".

7. Oct 17, 2004

### Tom McCurdy

true

I was assuming you weren't talking about instanious velocity or acceleration