How long will it take them to be 50 feet apart?

Question

Mrs. Smith challenged Sam to a duel with water pistols at 50 feet. They start walking in opposite directions. Mrs. Smith walks at 2 feet per second. Sam runs at 6 feet per second. How long will it take them to be 50 feet apart? 

Answer 1

Speed = distance/time ----> Distance = speed*time

 

The two of them have their own speed. Since you are targeting a specific distance, both of them should stop at the SAME TIME. Therefore mathematically, they will have the same time spent moving.

 

Total distance of 50 = Distance walked by Mrs. Smith + Distance ran by Sam

 

50 = Speed of Mrs. Smith*Time + Speed of Sam*Time

 

50 = 2*t + 6*t

 

50 = 8t

 

t = 50/8 = 25/4 = 6.25 seconds