Acceleration with Velocity Problem.

[kencamarador]

A boy is running a a constant velocity of 3.0 m/s [E] and passes his father who is standing still. The father immediately starts to chase his son with a constant acceleration of 1.5m/s at the instant his that his son reachers him

How long does it take the father to catch his son?

So to find time. I did

T= vf - vi/aav

Vf is final velocity (3.0-0)
Vi is initial velocity (0)
Aav is average velocity (1.5)

I got 2 Seconds? But the correct answer is 4? How?

 

[haruspex]

You calculated the time it would take the father to reach the same speed as the son. But he will still be some way behind the son.

 

[kencamarador]

You calculated the time it would take the father to reach the same speed as the son. But he will still be some way behind the son.

so what do I do though...

 

[haruspex]

Write equations for how far each will travel in time t after the son passes the father.

 

[Equilibrium]

at the instant his father catches his son, they all have the same distance from since the son passed his father, hence:
$$d_{father}=d_{son}$$

continue here