Posted by **Jason** on Tuesday, April 20, 2010 at 11:37am.

A motorist drives along a straight road at a constant speed of 60 m/s. At time t = 0 she passes a parked motorcycle

police o±cer. The o±cer takes o® after her at t = 0 and accelerates according to the formula a(t) = bt, where t is the

time and b is a positive constant. What is the speed of the police o±cer when he reaches the motorist?

- Physics -
**bobpursley**, Tuesday, April 20, 2010 at 11:48am
Well, they travel the same distance in the same time.

The officers velocity is INT a(t)dt= INT btdt= 1/2 b t^2

so the officers distance traveled is

INT 1/2 b t^2 dt= 1/6 b t^3

set the distances equal

1/6 b t^3= 60t

solve for t.

t^2= 360/b

t= sqrt(360/b)

now find the velocity of the officer at that point:

Vf= 1/2 b t^2= 1/2 b * 360/b=180m/s

check my work.

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