|TOPIC 08-WORK, ENERGY AND POWER

 

TOPIC 08-WORK, ENERGY AND POWER

WORK

Is the product between force applied and the distance in the same direction

Mathematically:

Work done = Force x distance → 𝑾.𝒅 = 𝑭 𝒙 𝒅

• The SI unit of work is Joule (J)

Joule is a force of 1N that moves an object through a distance of 1m in the same direction of the force

Equivalent Units of Work are:

1 Nm = 1 Joule = Kgm²S^-2 = 0.001 KJ

Examples of work done in daily life

1. When a person pushes a wall (No work is done since d = 0 m)
2. When a farmer carrying a hole (No work done since d = 0 m)
3. Lifting a pen (Work is done since d > 0 m)
4. Lifting a cup (Work is done since d > 0 m)

Example

1. A sack of maize which weighs 800N is lifted to a height of 2 m. What work done against gravity

Solution:

Wight, w = 800 N

Distance, d = 2 m

Work done, W.d =?

From:

W.d = F x d

W.d = 800 x 2 = 1600 J

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