Natural Sciences Grade 7 Term 3 Energy and

Natural Sciences Grade 7 Term 3: Energy and Change Potential and kinetic energy

Topic 2 Potential and kinetic energy What is energy? Natural Sciences - Grade 7

What is energy? • Energy is the ability to do work. • Energy cannot be created or destroyed. It is only changed from one type of energy to another. • The sun is our main source of energy. • Energy can be divided into two main forms, namely potential and kinetic energy. Natural Sciences - Grade 7

Energy • Energy is all around us - most of the time we are not even aware of it. • Plants use the light energy from the sun to make food during photosynthesis. • Animals and plants need food to get energy for all living processes. Natural Sciences - Grade 7

Energy • Wind is air particles in motion because the particles have energy. • The sounds we hear is also a form energy. • We burn coal and other fuels to release energy. Natural Sciences - Grade 7

The different types of energy There are five different types of energy: • Heat • Chemical • Electromagnetic • Nuclear • Mechanical Natural Sciences - Grade 7

Two main forms of energy All energy types can be divided into two main forms: • Potential energy - Energy that is stored within objects or systems. • Kinetic energy - Energy possessed by objects or a system as a result of movement. Natural Sciences - Grade 7

Examples of potential energy Elastic energy when a rubber band is stretched. Chemical energy that can change to electrical energy when using a cell. Gravitational potential energy. The ball and the brick gain energy when lifted from the ground. Natural Sciences - Grade 7

Examples of kinetic energy A pogo stick, when someone jumps on it, has kinetic energy, due to its motion. A racing motorcycle has lots of kinetic energy. The ball gains kinetic energy when kicked. Can you think of other examples of moving objects or systems? Natural Sciences - Grade 7

A closer look at gravitational potential energy • All objects (matter) will experience the force of gravity. • Gravity is the force causing all objects to fall to the ground. • The higher an objected is lifted, the greater the potential energy. • The heavier an object, the greater its potential energy. Natural Sciences - Grade 7

A closer look at gravitational potential energy • When the object falls to the ground, the potential energy changes into kinetic energy (because it moves). • When the object rests on the ground, it has no potential energy. Natural Sciences - Grade 7