Natural Sciences

Presented By: Mrs Young

Pitlochry Primary School Educator

What have we learnt so far?

Key concepts• Energy is one of the requirements for life on Earth.• Energy is needed to make things move.• Sources of energy have energy stored within them that is used to make something

happen.• Non-renewable energy sources cannot be re-used or recycled. There is a limited supply.• Examples of non-renewable energy sources include fossil fuels (oil, coal and natural gas)

and nuclear fuels.• Burning of fossil fuels release greenhouse gases into the atmosphere.• Renewable energy sources can be re-used or recycled. There is an unlimited supply.• Examples of renewable energy sources include wind, hydropower, solar power and

biofuels

Potential and Kinetic Energy

potential energy

kinetic energy

potential and kinetic energy in

systems

law of conservation of

energy

mechanical

thermal

electrical

biological

energy of movement

transferred in a system

transferred between systems

energy in food

stored in system

Potential Energy

KeywordsSystem – a set of parts that work together as a whole.Potential energy – stored energy that has the capacity to do work.

Potential energy is usually held in a system.

Energy stored in chemicals

Food Electricity Energy stored in stretched

objects

Energy stored in objects above ground because of

gravity

Read pg 42 and 43 in Exam Fever and page 116 and 117 in your textbook

Potential energy is usually held in a set of parts that work together (a system). An elastic band stretched on your finger has potential energy. It has stored energy that has the capacity to do work if it is set free by letting go of the elastic.

A cell in a torch or a mechanical toy has potential energy. The cell is storing energy that it can release to make the bulb glow.

Petrol is stored energy that will cause a car to move.

We get all our energy for living from the food we eat. There is potential energy in the food we eat which our bodies can turn into energy for living. Scientists measure energy in a unit called the joule. Since a joule is only a very small amount we often use kilojoules instead. A kilojoule is 1000 joules. Look at nutritional information labels to find out how many kilojoules are stored in that food.

Potential Energy

Let’s investigate

Record your results in your activity booklet

Kinetic Energy

Kinetic energy is the energy a body has because of its movement. Potential energy only has the capacity to do work in the future. Kinetic energy is doing the work at the time.When the elastic band is stretched it has potential energy. When it is released it has kinetic energy. When water runs over a waterfall it has kinetic energy. When a car is moving it has kinetic energy. In each example the potential (stored energy) has turned into kinetic energy (to do work and cause a change).

Summary

Activity pagesQuestion 1Complete the table by giving an example.

Type of energy Example

Energy stored in chemicals

Energy stored in food

Electrical energy

Energy stored in objects above ground because of gravityEnergy stored in stretched objects

Record results

Height of marble up the ramp Distance the cup moves

Question 3Use the information in your table to draw a graph of the height of the marble up the ramp versus the distance the cup moves.

Take note: The independent variable is the value which you changed (the height f the ramp). The independent variable is written on the x axis (horizontal axis). The dependent variable is the value you measured (the distance the cup moved). The dependent variable is written on the y axis (vertical axis).

Question 2

References

• Top Class Natural Sciences Grade 7, P. Ayerst, D. Smith, M. Hill, Shuter and Shooter, 2013

• Exam Fever Natural Sciences Grade 7, G. Ramlall, M. Maipath, T. Pillay, Exam Fever, 2020

https://www.pitlochryps.co.za/