Question

A motorist travels at a constant speed of 34.0 m/s through a school zone; exceeding the posted speed limit. A policeman, waits 7.0 s before giving chase at an acceleration of 3.9 m/s2.

(a) Find the time required to catch the car, from the instant the car passes the policeman.
2 s

(b) Find the distance required for the policeman to overtake the motorist.
3 m

Answer 1

Are 2s and 3 m your answers? Please show your work

Answer 2

I actually don't know where the 2s and 3m came from, I think it was a typo on my MSWord

Answer 3

(a) Measure time t from the instant the policeman passes the cop.
The speeder's distance travelled is
X1 = 34 t meters
The policeman's distance travelled (for t>7) is
X2 = (1/2)*3.9 (t-7)^2
Set X1=X2 and solve for t.
That is when the speeder is caught.

Answer 4

15.97