In this module, you will learn:

  • A force is a push or a pull
  • The different types of forces
  1. Friction
  2. Gravity
  3. Magnetic forces

Resources to help you:

  • Textbook: page 110 to 117
  • Notebook: page 36


Watch the video

See what is a force and how it affects objects.

Source: https://www.youtube.com/watch?v=xUCYFof8QyA

You can change the speed to 0.75x to make it easier to listen.

A parachute slows down the descend of the man due to forces.

Credit: @RumRiverPhotography via Twenty20

Types of Forces


A force is a push or pull. It can be both a push and a pull too.

Some examples of the forces you are familiar with are pushing, pulling, bending, lifting and stretching.


There are also forces that affect us and the things around us.

They are:

  1. Friction
  2. Gravity, and
  3. Magnetic forces

Friction


When two surfaces come in contact and move against one another, we get friction. Friction is a force that opposes (tries to stop) movement.


The type of surface will determine the amount of friction. For example, a smooth surface like glass will have less friction than a rough surface like carpet.


Reading tasks:

  • Read pages 113 and 114 of your textbook (Y7) to find out the importance of friction and the disadvantages of friction.
  • Read page 115 of your textbook (Y7) to find out how you can reduce friction.

Source: https://www.youtube.com/watch?v=C7NPD9W0kro

Learn more about Gravity

Source: https://www.youtube.com/watch?v=suQDwZcnJdg

Learn more about the differences between mass and weight

Source: https://www.youtube.com/watch?v=Y8-T8RouhPA

Gravity


When you jump, you come back down. The force at play here is gravity.

An object that has mass will have gravity. We feel the effect of gravity towards the centre of the Earth because it is much bigger than us.


The pull of gravity towards the centre of the Earth also gives us our weight. Weight is a force (measured in newtons) and can change depending on the gravity. This is why we have less weight on the moon than on Earth.

This is different from the mass which is a constant. Mass is the amount of substance in a body, and is measured in grams or kilograms.

Magnetic Forces


A magnetic force is the force of attraction or repulsion of magnets or magnetic materials.


A magnet has two poles, North and South.

If the poles are the same, e.g. North - North and South - South, they will repel. We call this force repulsion.

If the poles are different, e.g. North - South or South - North, they will attract. We call this force attraction.


Source: https://www.youtube.com/watch?v=yXCeuSiTOug

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