# Help with velocity problem

1. Apr 25, 2005

### chound

The position of an object moving along x-axis is given by x=a+b(t*t) where a =8.5m, b=2.5m/(s*s) and t is time. What is the velocity at t=2s? I think differential calculus should be used

2. Apr 25, 2005

### whozum

If that x equation is x = a+bt^2, then just differentiate wrt to time to get velocity.

3. Apr 25, 2005

### futb0l

Yupp, just get dx/dt and then make t = 2.

4. Apr 26, 2005

### chound

Is it this:
dx/dt = d(a+bt^2)/dt
After this what should I do?

5. Apr 26, 2005

### James R

Do you know how to differentiate?

If $y = a + bx^2$, what is dy/dx?

You have $x = a + bt^2$, and you know v=dx/dt, so what is v(t)?