# Calculating time from velocity and acceleration?

## Main Question or Discussion Point

Simple? You would think so , see if you agree with my approach...

I have a car, I know its power at certain Rpm's and I know the magnitude of resitive forces.

So
1. I calculate the power loss due to resitive forces
2. I calculate the net power by subtracting this from motive power.
3. I calculate the velocity from the Rpm of the motor, through gearing down to wheel speed and then tangental velocity.
4. I calculate the net force by dividing by velocity.
5. Dividing by the mass gives me the max acceleration at a particular rpm.

Now i want to calculate how quickly i can accelerate from 0-30 m/s (for example) so using a=dv/dt and rearranging for dt = dv/a i should be able to calculate how long it takes to accelerate from a certain speed at a certain acceleration.

Would people agree with this approach

One problem with this is for this motor, and most other motors, the power at 0 rpm is zero, so i should probably use the torque curve rather than the power???????????????????????????????