Police car catching speeder with constant acceleration

[moondawg]

Homework Statement

A police car traveling at 46m/s is passed by a speeder traveling at 72 m/s. Precisely 1s after the speeder passes, the police car accelerates after him. He catches him 7s later.
how fast is the police car going as he catches him?
how far did the speeder get before being caught?

Homework Equations

x=vt
x=x_o+v_ot+1/2at²
v=v_o+at

The Attempt at a Solution

I calculated that the speeder traveled 576m then plugged that into the 2nd equation above to find the police cars acceleration then plugged that acceleration into the 3rd equation to get the police cars velocity when he catches the speeder=105.43m/s... and found that the speeder got 576m before being caught.
I am not too sure if I did this correctly, someone please check me?!

 

[Redbelly98]

The Attempt at a Solution

I calculated that the speeder traveled 576m then plugged that into the 2nd equation above to find the police cars acceleration then plugged that acceleration into the 3rd equation to get the police cars velocity when he catches the speeder=105.43m/s... and found that the speeder got 576m before being caught.
I am not too sure if I did this correctly, someone please check me?!

I see a problem, which is that the police car was not accelerating for the entire 8 seconds. It continued at 46 m/s for 1 s, and then accelerated for 7 seconds. So think about these questions:

• How far did the police car go in that first second?
• How far did the police car have to go during the remaining 7 seconds, in order to catch the speeder?

 

[moondawg]

thankyou (: