Question

You lift a heavy book from the floor of the room and put it on the book shelf having a height 2m. In this process you take 5s. The work done by you will depend upon
A. Mass of the book and time taken
B. Weight of the book and the height of the book shelf
C. Height of the book shelf and time taken
D. Mass of the book, height of the book shelf and time taken

Answer 1

Hint:
- You should know the definition of work.
- You should know force and displacement.

Complete step by step Solution:
Word is the measure of energy transfer that occurs when an object is moved over a distance by an external force at least part of which is applied in the direction of the displacement. ... To express this concept mathematically, the work W is equal to the force F times the displacement s,
\[
  W = F \cdot s \\
  W = Fs\cos \theta \\
 \]
A force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. When the interaction ceases, the two objects no longer experience the force.
Displacement is a vector quantity that refers to "how far out of place an object is"; it is the object's overall change in position. That is the final position – initial position.
\[\overrightarrow s = {s_f} - {s_i}\]
So from question,
Work done\[ = Force \times displacement\]
Force\[ = weight\;of\;book\]
\[
  F = ma \\
  F = mg = weight \\
 \]
Displacement\[ = height\;of\;shelf\]

So, Option (B) is the correct answer.

Note:
- Memorize basic definitions.
- Should have a good conceptual clarity in force.