3.5 Machines make work easier

Natural sciences

Grade 9

Energy, forces and machines

Module 23

Machines make work easier

Activity:

Comparing a variety of appliances

[lo 1.3; lo 2.2; lo 2.3]

A machine is a technologically designed apparatus that can perform work through the conversion of energy from one form to another.

• Energy makes work possible.
• Work involves transfer of energy.
• The amount of energy that is applied is equal to the performance that is provided.

Small machines have the capacity to effectively provide the power that human beings are simply unable to provide.

When you buy small electrical appliances that have to perform work, you ought to check the kilowatt power. By doing this you will be able to determine whether you will obtain the required performance.

Case Study

Comparing APPLIANCES

• You want to buy a hairdryer as a birthday present for your sister and a kettle to replace your mother's kettle, which has stopped working.
• Your sister gets up late, but washes her hair every day. She spends 20 minutes blow-drying it every morning.
• Your mother regularly makes tea for the family and for friends who come to visit. This comes to at least four cups of tea a time, at least five times per day.

Compare appliance models of your choice and prices at a wholesaler. Also investigate performance and make a suggestion concerning what you are able to buy.

• Write a brief report on your findings.

Assessment of CASE STUDY regarding appliances

Were you able to interpret the information and apply knowledge?

[LO 1.3; LO 2.2; LO 2.3]

Assessment

LO 1: Scientific investigations:

The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

This is evident when the learner:

1.3 evaluates data and communicates findings.

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:

• recalls meaningful information;
• categorises information;
• interprets information.

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