## ilikephysics2 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 3.7 m/s2. one year ago one year ago

1. ilikephysics2

Find the time required to catch the car from the instant the car passes the policeman.

2. ilikephysics2

Find the distance required for the policeman to overtake the motorist.

3. zaphod

For Car ( insert the values and get an equation) s = ut s = 34 t ------> (1) equation For Policeman ( he starts 7 s later so it is (t-7)) s= ut + 1/2 at^2 ( u = 0) as he strts frm rest $s = \frac{1}{2} \times 3.7 \times (t-7)^{2}$ $2s = 3.7(t^{2}-14t+49)$ $2s = 3.7t^2 -51.8t +181.3$ Now plug in equation {1} in to s so $2(34t) = 3.7t^{2}-51.8t+181.3$ i think now u can solve and find time.

4. zaphod

did u get it ...

5. ilikephysics2

no?

6. zaphod

ok which one u dont understnd?

7. ilikephysics2

im at 3.7t^2 - 119.8t + 181.3 = 0 now im working on the quadratic equation but I keep getting it wrong please help

8. zaphod

u can either use the calculator or this formula

9. ilikephysics2

i tried the calculator and it keeps saying error

10. zaphod
11. zaphod

or insert the values in this http://www.math.com/students/calculators/source/quadratic.htm