Question

What force will change the velocity of an object of mass $2.5Kg$ from $5m{s}^{-1}$ to $10m{s}^{-1}$ in 5 seconds?

• A. 2.5 N
• B. 5 N
• C. 10 N
• D. 7.5 N

Answer 1

The correct option is A

2.5 N

Step 1: Given data

Mass of the object, $m=2.5kg$

The initial velocity of the object, $u=5\frac{m}{s}$

The final velocity of the object, $v=10\frac{m}{s}$

Time, $t=5sec$

Step 2: Formula used

By the first equation of motion

$v=u+at$

$a=\frac{v-u}{t}$

Step 3:Calculation of acceleration

$$\begin{gathered} a=\frac{10m/s-5m/s}{5s} \\ a=\frac{5m/s}{5s} \\ a=1\frac{m}{s^2} \end{gathered}$$

Step 4: Calculation of force

$$\begin{gathered} F=m\times a \\ F=2.5kg\times 1\frac{m}{s^2} \\ F=2.5N \end{gathered}$$

Hence, the correct option is A.