Question

The initial velocity of a particle is $10\text{m/s}$ and its retardation is $2{\text{m/s}}^2$. The distance moved by the particle in $5^{\text{th}}$ second of its motion is:

• A. $1\text{m}$
• B. $19\text{m}$
• C. $50\text{m}$
• D. $75\text{m}$

Answer 1

The correct option is A $1\text{m}$

$u=10\text{m/s}$
$a=-2{\text{m/s}}^2$

The distance covered by a particle in $n^{\text{th}}$ second is given by:
$S_n=u\left(1\right)+\frac{1}{2}a(2n-1)$
$S_5=10+\frac{(-2)}{2}(2\times 5-1)$
$S_5=10-9=1\text{m}$