Hey Mark. Hopefully my education in the metric system will help. I'm horrible at math, so I may not be able to help with the calculations.

There's a good reason why the question was posed in km/h. Here's why - and it's because of the simplicity of the metric system.

1 km = 1000 meters.

So, a vehicle traveling at 100 km/hr will travel (100x1000)m/hr. or 100,000 m/hr or 27.78m/sec (see explanation below).

I'm not sure how the acceleration expressed in seconds sqaured impacts it but if he accelerates at 3m/second, you'll have to figure out how many seconds to get to 120 kmh. at that point, you'll know how many meters he travelled (3 x seconds squared).

At the same time, you'll have to figure out how far the speeder traveled in the same time and factor that distance in at 120,000 m/hr, which works out to 120,000 m/(60min x 60 seconds/minute) which is 120,000m/3600 seconds or 33.33 m/sec. and determine the total distance to get to the speeding vehicle.

Metric makes the calculations much simpler.

Hope this helps...

TOM