Work

What is work?

Work is the result of displacement of an object with force.

In our daily lives, everyone performs work whether intentional or not. For instance, during midday when the sun is in the sky, any individual would wear sunglasses to prevent eye damage from occurring. The act of lifting the sunglasses from its case is considered as work since the sunglasses are being moved from the case to the eye area. So there is force and displacement given during this performance.

What is not work?

There is no work if the force doesn’t cause any movement on the object, or if the force and the displacement appear in opposite directions. In the event that this happens, the work will be zero.

As mentioned before, the process in placing the sunglasses on is regarded as work. However, it is not work when wearing the sunglasses due to the fact that there is no movement/displacement even though there is force in the performance.

Unit of measurement

·      Work: Joules (J)

·      Force: Newtons (N)

·      Displacement: Meters (m)

Formula of work

W = F d

·      W = Work

·      F = Force

·      d = Displacement

The formula above states that the force applied on an object multiplied by the displacement of the same object is work. However, in some cases there could be two forces acted on one object going in the same direction. In this occurrence, you must add the two forces together then multiply the result by the displacement. On the other hand, if the two forces proceed in opposite directions you must subtract the forces.

Examples

a.     A customer is pushing a cart at 11N down a straight 8m aisle while shopping in a grocery store, what is the work?

Answer:

W = F d

W = 11 x 8

W = 88 J

b.     What is the work if two people wanted to move a table 3m away? The first person pushes at 18N and the other at 13N?

Answer:

W = F d

W = (18 + 13) x 3

W = 31 x 3

W = 93