A transport plane has two gliders tied behind it. The max force allowable on the tow rope is 12000N. The mass of each glider is 700kg. A velocity of 40 m/s is required to take off. What is the minimum runway space required. The solution I have arrived at doesn't seem correct, hopefully someone can tell me where I have strayed off the path. F = ma 12000 = (700+700)a a = 12000/1400 a = 8.57 m/s^2 V = V(init) +at 40 = 0 +8.57t t = 40/8.57 t = 4.67s S = 1/2(a)t^2+V(init)t + S(init) 1/2(8.57)(4.67^2) + 0 + 0 = 20 meters I don't think the plane could reach 40 m/s in 4.67 seconds and it would have to be a really small transport plane to take off in 20 meters. Hopefully someone can point out where I went wrong. Thanks for the help.