Shrinking Distance Between Travelers on Kiss and Quarrel

[afashoro]

Conceptually I'm having a hard time fully grasping why it makes sense to add the rates together (assuming the travelers are moving simultaneously) in order to find the rate of the shrinking/growing distance between travelers.

[chitrangada.maitra]

Hi,

The rates are added only if both these criteria are met.

1. the objects are moving simultaneously
2. the objects are moving towards each other

Lets say a man is walking towards a coffee shop, 10 km away at a speed of 5 km/hr. It will take him 2 hours to reach the coffee shop.

What we did here is distance / speed or 10/5=2

Again, lets say the coffee shop decides to move towards the man (wild, I know). Starting distance between the man and the coffee shop is the same i.e. 10 km. Lets say the coffee shop is walking towards the man at 5km/hr.
So, the time it takes for the man to get his coffee should be less because now two people are making the effort of walking.

It will take them 1 hour to meet.
What we did here is 10/5+5=1

distance/speed of man+speed of coffee shop.

Hope that helps,

[afashoro]

Hi,

Thank you very much. This helps a lot conceptually.

Thank you again for taking time to answer.

[tim]

:)