At the point at which two cars pass each other going in opposite directions is the speed relative ?

Question

For example, if one car is traveling at 40mph and an oncoming car is also traveling at 40mph, when they pass, does this mean the speed of the opposite car is viewed as faster or even doubled from the point of the one car?

 

It's 3 a.m. and my mind is blown by thinking stupid thoughts.. Whoever gives the best answer gets free nuggets

Answer 1

Here is the rule to remember when both bodies are moving along the same straight line:

 

If they are moving in opposite directions, the relative speed is the sum of the speeds.  If they are moving in the same direction, the relative speed is the difference of the speeds.  

 

For example, if car A is moving to the right at 40 mph and car B is moving to the left at 30 mph, a rider in car A sees car B moving at 40 + 30 = 70 mph.  That is true as they approach each other from opposite directions and remains true after they have moved past each other.  Similarly, a rider in car B sees car A moving at 70 mph.

 

But if both cars are moving to the right, car A at 40 mph and car B at 30 mph, a rider in car A sees car B moving at 40 - 30 = 10 mph.  This is valid when the fast car is behind the slow one, and remains true after the fast car passes the slow one.

 

Does this help?