Question

A car moving at a speed $v$ is stopped by a retarding force $F$ in a distance $s$. If the force of the car is $3F$, car stops in a distance:

• A. $\frac{s}{3}$
• B. $\frac{s}{6}$
• C. $\frac{s}{9}$
• D. $\frac{s}{12}$

Answer 1

The correct option is A $\frac{s}{3}$

let the mass of car be m

retardation $a=\frac{F}{m}$

now using $v^2-u^2=2as$ ,here final velocity is zero , we get $v^2=2\frac{F}{m}s$ .....(1)

now the force be $3F$

let the distance be $s_1$

retardation $a=\frac{3F}{m}$ velocity is $v$

$(v{)}^2=2\frac{3F}{m}{s}_1$ .....(2)

from (1) and (2)

$s_1=\frac{s}{3}$