Q. A body starting from rest moves with constant acceleration. The ratio of distance covered by the body during the 5 th second to that covered in 5 s is
A) $\frac{9}{25}$
B) $\frac{3}{5}$
C) $\frac{25}{5}$
D) $\frac{1}{25}$
Explanation
(a) Distance covered in 5 s
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ s_{1} = \frac{1}{2}\ at^{2}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \frac{1}{2}a(5)^{2} = \frac{25a}{2}$
Distance covered in 5$^{th}$ second
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ s_{2} = \frac{1}{2} \times a(2 \times 5 - 1) = \frac{9}{2}\ a$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{s_{2}}{s_{1}} = \frac{9}{25}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.