A body is travelling towards East with a speed of 9 m / s and with an acceleration of 2 m / s 2 acting along West on it. The displacement of the body during the 5 text th second of its motion is

Question

A body is travelling towards East with a speed of 9 m / s and with an acceleration of 2 m / s 2 acting along West on it. The displacement of the body during the 5 text th second of its motion is (A) 0.25 m (B) 0.5 m (C) 0.75 m (D) zero

Tardigrade Admin · Accepted Answer

Displacement in the nth second is given by

S_{n} = 4 + \frac{a}{2} (2 n - 1)

In this problem retardation is involved.
Thus, the equation becomes

S_{n} = 4 - \frac{a}{2} (2 n - 1)

Given

u = 9 m / s, a = 2 m / s

n = 5

\Rightarrow S_{5} = 9 - \frac{2}{2} (2 \times 5 - 1)

= 9 - 9 = 0

Q. A body is travelling towards East with a speed of 9m/s and with an acceleration of 2m/s2 acting along West on it. The displacement of the body during the 5th second of its motion is

0.25 m

0.5 m

0.75 m

zero

Displacement in the nth second is given by Sn​=4+2a​(2n−1) In this problem retardation is involved. Thus, the equation becomes Sn​=4−2a​(2n−1) Given u=9m/s,a=2m/s n=5 ⇒S5​=9−22​(2×5−1) =9−9=0

Q. A body is travelling towards East with a speed of $9 m / s$ and with an acceleration of $2 m / s^{2}$ acting along West on it. The displacement of the body during the $5^{th}$ second of its motion is

Displacement in the nth second is given by
$S_{n} = 4 + \frac{a}{2} (2 n - 1)$
In this problem retardation is involved.
Thus, the equation becomes
$S_{n} = 4 - \frac{a}{2} (2 n - 1)$
Given $u = 9 m / s, a = 2 m / s$
$n = 5$
$\Rightarrow S_{5} = 9 - \frac{2}{2} (2 \times 5 - 1)$
$= 9 - 9 = 0$