A car starting from rest, accelerates at the rate of f through a distance S, then continues at constant speed for time t and declerates at the rate f//2 to come to rest. If the total distance travelled is 15 S then S =

A car starting from rest, accelerates at the rate of f through a dista

1.	A car starting from rest, accelerates at the rate of f through a distance S, then continues at constant speed for time t and declerates at the rate f//2 to come to rest. If the total distance travelled is 15 S then S =
Answer» Solution : `AB=S=(1)/(2)ft_(1)^(2)......(1)v=ft_(1)` `BC=vt=(ft_(1))t......(2)` `CD=(u^(2))/(2a)=((ft_(1))^(2))/(2(F//2))=2S......(3)` `S=ft_(1)t+2S=15S` `ft_(1)t=12S......(4)` Dividing (4) by (1) `t_(1)=(t)/(6)` Now (1) gives `S=(1)/(2)f""(t^(2))/(36) THEREFORE S=(ft^(2))/(72)`