# What is the average speed, on t in [0,5], of an object that is moving at 12 m/s at t=0 and accelerates at a rate of a(t) =5-2t on t in [0,4]?

Dec 27, 2015

The average speed is 9.6 m/s

#### Explanation:

You must consider the equations
$s = s + v t + \frac{1}{2} a {t}^{2}$
and divide the total path into two parts, one with acceleration and one without acceleration. You find the total distance and the time elapsed and finally use the equation:
$s p e e d = \frac{\mathrm{di} s \tan c e}{t i m e}$
That's all.