Question

A body of mass $3\text{kg}$ moves with an acceleration of $3{\text{m/sec}}^2$ . The change of momentum per unit time is $P\left(\text{kg m/sec}\right)$. What is the value of $P$ ?

• A. $3\text{kg m/sec}$
• B. $9\text{kg m/sec}$
• C. $4\text{kg m/sec}$
• D. $1\text{kg m/sec}$

Answer 1

The correct option is B $9\text{kg m/sec}$

Mass of the body is $3\text{kg}$ and acceleration is $3{\text{m/s}}^2$,
applying $F=ma$ we have
$F=3\times 3=9\text{N}----\left(1\right)$
$\therefore$ Force applied to the body is proportional to change in momentum, so,
$F=\frac{\Delta P}{\Delta t}----\left(2\right)$
From eq $\left(1\right)$ and $\left(2\right)$
$9=\frac{\Delta P}{1}$
$\Delta P=9\text{N}\times 1$
Therefore, $P=9\text{kg m/s}$