Q. A body starting from rest moves with constant acceleration. The ratio of distance covered by the body during the 5$^{th}$ $\sec$ to that covered in $5\ sec$ is

A) $9/15$
B) $3/5$
C) $25/9$
D) $1/25$
Explanation

(a) Distance covered in $5^{th}$ second
$S_{5^{th}} = u + \frac{a}{2}(2n - 1) = 0 + \frac{a}{2}(2 \times 5 - 1) = \frac{9a}{2}$
and distance covered in $5\ second$,
$S_{5} = ut + \frac{1}{2}at^{2} = 0 + \frac{1}{2} \times a \times 25 = \frac{25a}{2}$
$\therefore\frac{S_{5^{th}}}{S_{5}} = \frac{9}{25}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.