1.1 Let's look at levers

Technology

Grade 5

Machines made easy

Module 2

Levers

Let’s look at levers

One of the easiest ways to lift a heavy object is by using a lever.

Assignment

1. What is a lever?

A lever is a beam that rests on something or that is attached to something and it works on this point of support or fulcrum.

1. How does a lever work?

By applying a force a heavy load can be moved relatively easily.

1. We get three main types of levers, namely:

Type1: A lever where the fulcrum is between the load and the force, e.g. a balancing scale.

Type 2: A lever where the load is between the force and the fulcrum, e.g. a wheelbarrow.

Type 3:

A lever where the force is between the load and the fulcrum, e.g. a man who is fishing.

1. INVESTIGATION.

Do the following experiments on the type 1 lever in groups.

1. What materials do you need?

a long metal woodwork ruler;

a small block of wood / eraser / round container

a medium-sized coffee tin with a lid / a pill container

drawing pins / paper clips

Experiment 1

• Aim:

To determine how a lever works.

• Method:

Make a lever by placing the metal rule on the block of wood.

Place the block of wood under the 15 cm mark on the ruler.

Fill the tin halfway with sand.

Place the tin of sand on the 0 cm mark on the ruler.

Now press on the ruler at the 30 cm mark.

Fill the tin completely with sand.

Press on the ruler at the 30 cm mark again.

Lift the empty tin and note how heavy it is.

• Observation :

Is the half filled container lifted?

Is the full container lifted?

• Conclusion :

Was it just as difficult as when you tried to lift the tin by yourself?

Assignment

Make a sketch with labels of experiment 1.

[LO 1.12]

1. Experiment 2

1. Aim :

To determine what will happen if we move the fulcrum.

1. Method :

1. Place the block of wood under the 20 cm mark on the ruler.

Place the half-filled container with drawing pins on the 0 cm mark on the ruler.

Now press on the ruler at the 30 cm mark.

OR

1. Place the block of wood under the 10 cm mark on the ruler.

Place the filled container with drawing pins on the 0 cm mark on the ruler.

Now press on the ruler at the 30 cm mark.

1. Observation :

Choose the correct word in brackets:

It is easiest to lift the container with drawing pins when the fulcrum is ( closest to/furthest away from ) the container with drawing pins. The experiment that proves this is attempt 2 (X / Y).

In attempt 2 (X / Y) the distance that you have to press down is the shortest.

1. Conclusion :

The further away the pressure is from the (pivot / fulcrum), the greater is the pushing force exercised on the container, therefore making it easier to lift.

1. Experiment 3

1. Aim :

To determine where to push on a lever to obtain the best result.

What materials do you need?

A ruler.

A pencil.

2c coins.

1. Method :

Place the pencil under the ruler in the middle. Place a coin at the one end of the ruler.

Let the other coin fall from a height of 30 cm to hit the ruler in the middle between the fulcrum and the other end.

1. Observation :

Complete the illustration by drawing your observation.

Repeat steps 1 and 2 of the method, but let the coins fall on the edge of the ruler.

• Observation : The coin shoots (higher/lower) if the coin falls on the edge.
• Conclusion : The further away the pressure from the fulcrum, the greater the pushing force.
• Self-assessment

How did my group do in the experiments?

Write down the names of the learners in the group.

Write “yes” or “know” next to numbers 1 to 8.

9. If your answer to 7 is no , answer the following questions:

1. Who did the most? Why?
2. Who did the least? Why?
3. Discuss your answers in your group. Have you learned anything from this assignment? If so, write down what you have learned.

[LO 1.3]

Assessment

LO 1

TECHNOLOGICAL PROCESSES AND SKILLS

The learner will be able to apply technological processes and skills ethically and responsibly, using appropriate information and communication technologies.

We know this when the learner:

Investigates:

1.2 finds out about existing products relevant to a problem, need or opportunity, and identifies some design aspects (e.g. who it is for, what it looks like, what it is for, what it is made of);

• performs, where appropriate, scientific investigations about concepts relevant to a problem, need or opportunity using science process skills:

1.3.1 planning investigations;

• conducting investigations;

1.3.3 processing and interpreting data;

1.3.4 evaluating and communicating findings.

Makes:

1.7 outlines a plan that shows the steps for making, including drawings or sketches of main parts;

1.8 uses suitable tools and materials to make products by measuring out, cutting or separating, shaping or forming, joining or combining, and finishing the chosen material;

Evaluates:

1.10 evaluates, with assistance, the product according to the design brief and given specifications and constraints (e.g. people, purpose, environment), and suggests improvements and modifications if necessary;

1.11 evaluates the plan of action followed and suggests improvements and modifications if necessary;

Communicates:

• produces labelled two-dimensional drawings enhanced with colour where appropriate.

LO 2

TECHNOLOGICAL KNOWLEDGE AND UNDERSTANDING

The learner will be able to understand and apply relevant technological knowledge ethically and responsibly.

We know this when the learner:

Systems and control:

• demonstrates knowledge and understanding of how to use energy sources to power mechanical systems in order to make a product move in some way.