Question

The work done in lifting a mass of $1kg$ to a height of $9.8m$ is

• A. $1J$
• B. ${\left(9.8\right)}^{2}J$
• C. $9.8J$
• D. None of these

Answer 1

The correct option is B ${\left(9.8\right)}^{2}J$

Work done = force $\ast$ displacement

and force = mass $\ast$ acceleration

Also acceleration = gravity and displacement = height

Therefore Work = mgh = 1 $\ast$ 9.8 $\ast$ 9.8 = (9.8)${}^2$ J

Hence work done is (9.8)${}^2$J