Question

A car, starting from rest, accelerates at the rate f through a distance S, then continues at: constant speed for time t and then decelerate at the rate $\frac{f}{2}$ to come to rest. If the total distance travelled is 15S, then

• A. $S= f t$
• B. $S=\frac{1}{6}ft^2$
• C. $S=\frac{1}{72}ft^2$
• D. $S=\frac{1}{4}ft^2$

Answer 1

Answer: (C)

$S=\frac{1}{72}ft^2$

Answer 2

$\frac{1}{2} \, ft^2_1 = s$ $f_2 = f /2 \, \Rightarrow \, S_2 = 2s v$ $\nu = ft_1 \, \Rightarrow \, t_1 = \frac{12S}{ft}$ & $S = \frac{1}{2} ft^2_1$