Pressure 03

This is our third KS3 Science quiz on pressure. For a given force, if it is acting on a smaller surface area, it will create a bigger pressure. Try cutting a fruit with the wide flat side of a knife. Now try the thin side - it will cut smoothly. The flat side has a greater surface area, therefore less pressure as the force is more spread out. Some of the questions that you will be asked about pressure will be about making comparisons between different objects, like in the example above. These test if you understand how pressure works. Other questions will test your knowledge of how to work out pressure, they will require you to do some calculations.

When people talk about suction, they imagine that it is a pull force. It is in fact a pushing force created by a difference in pressure. A good example is a vacuum cleaner. It creates an area of low pressure inside itself. Outside of the cleaner, the air pressure is normal but it is higher than inside. If you really understand pressure, you will realise that this creates an unbalanced force where the inside of the vacuum cleaner meets the outside world. The force created pushes dust and other objects into the vacuum cleaner.