# Homework Help: Speeding cars

1. Oct 11, 2005

### aznriceboiz5

At the instant the traffic light turns green, a car that has been waiting at an intersection starts ahead with a constant acceleration of 3.55 . At the same instant a truck, traveling with a constant speed of 21.0 , overtakes and passes the car.

How far beyond its starting point does the car overtake the truck?

How fast is the car traveling when it overtakes the truck?

Thanks for the help

2. Oct 11, 2005

### curly_ebhc

Ok you have two equations of motion 1 for constant velocity and one for constant acceleration.

Now you have two options.
Solve both equations for displacement/distance and make two data sets. I suggest graphing both data sets on a shared set of axes. Make time the hotizontal axis and position the vertical axis. This will give you the best sense of what is actually happening. Don't forget that the cars position will change as a smooth curve. This is the more time involved method.

Second method:
Use your eqns. Don't forget that the vehicles will pass when they have the same position (in this case displacement).

This is where I leave you for now. Good luck.