Item with Uniform Velocity intersects with Item with Uniform Acceleration

[QuickSkope]

Solved, thanks :D

 

[gneill]

Homework Statement

A speeder passes a stationary cop car going 120 km/h. The police car accelerates 7 m/s^2 constantly till he meets up with the speeder. Where do they intersect? What is their time and distance?

Homework Equations

Speeder is car 1, Police car is car 2.
not 100% sure, but I tried using these:
d1 = v * t
V2 = a * t
d2 = 1/2a * t^2

The Attempt at a Solution

Converted 120 km/h to 33+(1/3) m / s.

where does d1 and d2 = the same? When the police car catches up.

Where t is unknown, solve for t:
v*t = 1/2a * t^2
33.33 * t = 1/2(7) * t^2 (substitute values)
33.33t = 3.5t^2 (Do math)
33.33 = 3.5t (remove one t on either side)
9.523 = t

d = v * t

d = 33.33 m/s * 9.523

d = 317.4 m


It feels okay, but I've only been doing physics a short while, I really just need someone to tell me if I am right or wrong. Thanks.

Hi QuickSkope. Welcome to Physics Forums.

Your reasoning and calculations look fine.

 

[QuickSkope]

Okay cool, thanks :D

Thanks for the Welcome, you can probably lock/close this.