Question

The work done to take a body of mass 100 kg to the top of a building of height 20 m is (Acceleration due to gravity = 10 m s\textsuperscript{-2})

• A. 14700 J
• B. 15700 J
• C. 20000 J
• D. 30000 J

Hint:

\textbf{Work Done Against Gravity:} The work done to lift an object vertically is equal to its gain in gravitational potential energy, assuming no air resistance or other non-conservative forces. \textbf{Formula:} Work Done = mgh, where 'm' is mass, 'g' is acceleration due to gravity, and 'h' is the vertical height. \textbf{Units:} Mass in kg, height in m, and g in m/s\textsuperscript{2} will give work done in Joules (J).

Answer 1

The Correct Option is C

Step 1: Identify the given values.
Mass of the body (m) = 100 kg
Height of the building (h) = 20 m
Acceleration due to gravity (g) = 10 m s\textsuperscript{-2}
Step 2: Determine the formula for work done against gravity.
When a body is lifted to a certain height against gravity, the work done is equal to the change in its gravitational potential energy. Work Done (W) = Potential Energy (PE) = mgh Step 3: Calculate the work done.
W = 100 kg \( \times \) 10 m s\textsuperscript{-2} \( \times \) 20 m
W = 100 \( \times \) 200 J
W = 20000 J
Step 4: Select the correct option.
The work done is 20000 J, which matches option (3).