Question

A force of $15\text{N}$ acts on an object of mass $10\text{kg}$ for $12\text{s}$. The work done by this force is

• A. $1525\text{J}$
• B. $1620\text{J}$
• C. $2000\text{J}$
• D. $875\text{J}$

Answer 1

The correct option is B $1620\text{J}$

Given,
$F=15\text{N}$
$m=10\text{kg}$
$t=12\text{s}$
$u=0\text{m/s}$
Acceleration produced due to this force is
$a=\frac{F}{m}=\frac{15}{10}=1.5{\text{m/s}}^2$
Velocity of the object after
$12\text{s}$ is
$v=u+at$
$v=0+1.5\times 12$
$\Rightarrow v=18\text{m/s}$
Therefore, work done by the force is
$\Rightarrow W=△K.E$
$\Rightarrow W=K.E_f-K.E_i=\frac{1}{2}m{v}^2-\frac{1}{2}m{u}^2$
$\Rightarrow W=\frac{1}{2}\times 10\times {18}^2-0=1620\text{J}$