# Conceptual Physics Exercise Questions

1. Sep 29, 2012

### wls_3.14

I'm taking Conceptual Physics, which is the first science course I've taken in college, and I cannot seem to understand the Exercise questions. For example, "You're in a car traveling at some specified speed limit. You see a car moving at the same speed coming toward you. How fast is the car approaching you, compared with the speed limit?" Are these types of questions common sense questions, or can the answer be found in the textbook?

2. Sep 29, 2012

### HallsofIvy

Staff Emeritus
Suppose you are traveling at 60 mph (relative to the road) and the car is coming toward you at 60 mph. Imagine a point on the road between you. The distance between you and that point is decreasing at 60 mph. The distance between the other car and that point is decreasing at 60 mph. How fast is the distance between cars decreasing?

If that's not sufficient, suppose you are traveling at 100 meters per minute, the other car is moving toward you at 100 meters per minute, and there is a point exactly halfway between you and the other car, 100 m from each car. How long will it take you to reach that point? How long will it take the other car to reach that point? So the distance between you has gone from 200 meters to 0 in that time. How fast were you moving toward each other?