How long does it take an automobile traveling in the left lane at 60.0 km/hr to pull along side a car traveling in the right lane at 40.0 km/hr if the cars' front bumpers are initially 100 m apart?(adsbygoogle = window.adsbygoogle || []).push({});

I know the velocity of the car in the left is 60 and the velocity of the car on the right is 40. I also know it's imperative to find the velocity of the left car in relation to the right car in order to compare their distances. I found this to be 20 km/hr. What I don't know, however, is how to find out how far the car on the right goes before the car on the left reaches it. I know time is distance divided by velocity, so I figure that if I can find this distance and divide it by 20 km/hr, I'll have the time.

I also know the answer in the back of the book .. 18.0 seconds. The question is, how do I get it?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Relative velocity of two cars

**Physics Forums | Science Articles, Homework Help, Discussion**