Question

A body covers $20 \,m$, $22 \,m$, $24 \,m$, in $8^{th}$, $9^{th}$ and $10^{th}$ seconds respectively. The body starts

• A. from rest and moves with uniform velocity
• B. from rest and moves with uniform acceleration
• C. with an initial velocity and moves with uniform acceleration
• D. with an initial velocity and moves with uniform velocity

Answer 1

Answer: (C)

$D_{n}=u+\frac{a}{2}\left(2n-1\right) ; D_{8}=20\,m$ and $D_{9}=22\,m$
$\therefore 20=u+\frac{a}{2}\left(2\times8-1\right)=u+\frac{15}{2}a\quad\ldots\left(i\right)$
$\therefore 22=u+\frac{a}{2}\left(2\times9-1\right)=u+\frac{17}{2}a\quad\cdots\left(ii\right)$
On solving eqn. $(i)$ and $(ii)$ we get ;
$u = 5\, m \,s^{-1}$, $a = 2 \,m \,s^{-2}$