## ilikephysics2 Group Title 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. 2 years ago 2 years ago

1. ilikephysics2 Group Title

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

2. ilikephysics2 Group Title

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

3. zaphod Group Title

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 Group Title

did u get it ...

5. ilikephysics2 Group Title

no?

6. zaphod Group Title

ok which one u dont understnd?

7. ilikephysics2 Group Title

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 Group Title

u can either use the calculator or this formula

9. ilikephysics2 Group Title

i tried the calculator and it keeps saying error

10. zaphod Group Title
11. zaphod Group Title

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