Question

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

• A. 1 J
• B. $(9.8{)}^2$ J
• C. 9.8 J
• D. none of these

Answer 1

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

Work = Force $\ast$ displacement

and Force = Mass $\ast$ acceleration

Acceleration = gravity and displacement = height

Force = mg, Work = mgh i.e 1 $\ast$ 9.8 $\ast$ 9.8 = (9.8)${}^2$ J