Along a straight road through town, there are three speed-limit signs. They occur in the following order: 66 , 31 , and 19 mi/h, with the 31 -mi/h sign located midway between the other two. Obeying these speed limits, the smallest possible time tA that a driver can spend on this part of the road is to travel between the first and second signs at 66 mi/h and between the second and third signs at 31 mi/h. More realistically, a driver could slow down from 66 to 31 mi/h with a constant deceleration and then do the same thing from 31 to 19 mi/h. This alternative requires a time tB. Find the ratio tB/tA

Question

Along a straight road through town, there are three speed-limit signs. They occur in the following order:  66 ,  31 , and  19  mi/h, with the  31 -mi/h sign located midway between the other two. Obeying these speed limits, the smallest possible time tA that a driver can spend on this part of the road is to travel between the first and second signs at  66  mi/h and between the second and third signs at  31  mi/h. More realistically, a driver could slow down from  66  to  31  mi/h with a constant deceleration and then do the same thing from  31  to  19  mi/h. This alternative requires a time tB. Find the ratio tB/tA

Ashley · Answer

90.5x10^3 :)

Jackie · Answer

90.5x10^3 doesn't sound reasonable since it's a ratio but i went ahead and tried it and it didn't work i believe you have to combine the equations of motion i'm just not sure how to do it!