We have established that objects can be moved around by applying FORCES. The application of force means that WORK is performed. **WORK**is the scientific term used to refer to this application of force.

We say that 1 Joule of work is required to move the force of 1 Newton over a distance of 1 metre!

- Remember that effort actually indicates the use of energy. A Joule therefore indicates the amount of energy that is required to move 1N over a distance of 1 metre.

Questions:

1. How much effort do you apply when you:

a) drag a 10-N brick over a distance of 3 metres?

b) drag a brick with a mass of 2,5 kg over a distance of 5 m?

2. The energy value of a bar of chocolate is 300 **kJ. **How many 2,5-kg bricks will you be able to drag for a distance of 5 metres with this amount of energy?

3. How far will the energy provided by another bar of chocolate enable you to drag one such brick?

**You have made use of the formula**
**: **

**W = F **
**×**
** s **

**W :** Work**F : **Force** s : **Distance

- WFsThe placement of the letters in the triangle will help you to remember how to use the formula. Your educator will explain this to you.

- Now calculate how much energy will be required to move yourself over a distance of 10 metres.

Your educator will provide you with further exercises dealing with movement/acceleration.

Assessment of CALCULATION OF ENERGY USAGE (EFFORT)

[LO 2.3; LO 2.4]

**LO 2: Constructing Science Knowledge: **

The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

**This is evident when the learner:**

- interprets information;

2.4 applies knowledge.

Activity

Questions:

1. a) F × s = 10N × 3m = 30 Joule

b) F × s = (2,5 × 10) × 5 = 125J

2. 300 kJ = 300 000J divided by 125J = 2 400 bricks

3. 300 000J divided by 25N = 12 000 m = 12 km

- Energy required to move a learner over a distance of 10 m:

Learner's mass = A

W (energy) = F (force) × s (distance) = (A X 10) × 10m