Q 11-02-023NEETJEE MainMedium
A body moving with uniform acceleration covers $12$ m in the $3^{\text{rd}}$ second and $20$ m in the $5^{\text{th}}$ second of its motion. Its initial velocity and acceleration are respectively
Answer: (D) $2\ \text{m/s},\ 4\ \text{m/s}^2$
Concept. Distance in the $n$th second: $s_n = u + \dfrac{a}{2}(2n - 1)$.
Step 1. Equations.
$$u + 2.5a = 12,\qquad u + 4.5a = 20$$
Step 2. Solve. $2a = 8 \Rightarrow a = 4\ \text{m/s}^2$; $u = 12 - 10 = 2$ m/s.
Answer. $2\ \text{m/s},\ 4\ \text{m/s}^2$ (Option D).
Solution by Sreeraj P, M.Sc Physics