Time and Work

What is Time?

The countable duration when an action or an event takes place is called Time.

The action starts and ends in this very duration. In simple words, a clock tells us the current time.

In Physics, time is denoted by the symbol ‘t’.

Examples of Time-

A boy left his house at 3 pm and reaches his friend’s house at 4 pm. Thus, the time taken by the boy from his house to reach his friend’s house is from 3 pm to 4 pm is 1 hour.

Thus, time taken (t) = 1 hour.

A train left Station A at 5 pm and reaches Station B at 10 pm. Thus, the time taken by the train from Station A to reach Station B is from 5 pm to 10 pm is 5 hours.

Thus, time taken (t) = 5 hour.

What is Work?

Hitting, kicking, pushing something is not considered to work.

Work can be defined as the transfer of energy from the item, elements of the body to another item, element or body when a certain amount of applied force makes the body move from one position to another.

In simple words, a force is a simple push or pull on an object/body. One must remember that for work to happen the body must move or show some displacement.

The work done by someone or something on someone or something is denoted in Physics with a capital ‘W’.

And the given formula for Work is The product of the applied force (denoted by ‘F’) and the displacement of the object (denoted by ‘d’).

Work (W) = Force applied (F) x Displacement of the body (d).

W = F x d.

Example of Work-

A boy pushing boxes from his room to his backyard. He does a certain amount of work.

A worker loading and unloading a truck. Work is done when the worker picks up the boxes from one.

Note: Two things a student must keep in mind to know if work is done or not is that-

The object has to show a change in its location, it must move.

If the force applied on the body is on the right side of the body, then the body must also move in the right direction. The applied force and direction of displacement of the body must be the same (directly proportional).

For example- When u try to lift a bag, the bag is moved from where it first was and where it is after being picked up. A force is applied exactly in the same direction (upward) where the bag is being picked up.

Examples of Work done in Physics-

Change is the Displacement or Position- A man pushing a box from ‘Position A’ to ‘Position B’ or a towing car carrying another towed car.

Change is Direction or Speed-  A football player trying to tackle his opponents or a batsman during a cricket match hits the ball.

Change in size or shape- A compressed spring wen left jumps or an artist sculpting with clay.

Work and Time Relation-

To do a certain amount of work, a certain amount of time is taken. The quantity of work done in a certain given amount of time is called the Rate of Work (denoted by the letter ‘R’).

Thus, we have a formula for Rate of Work (R):

Amount of work done (W) = Time taken to do the work (t) x Rate of work (R).

W = t x R.

Note: The amount of time taken to do work is done is inversely proportional to the rate at which work is done.

Calculations-

Force is measured in Newton (N).

Distance is measured in terms of meters (m).

Work is measured in Joules (J)