Force and Pressure 1

What are Forces? A push or pull

Examples of Forces Squeezing Stretching Twisting Folding

Effects of Forces Object’s shape changes Object’s size changes Stationary object moves

Effects of Forces Moving object stops Moving object speeds up or slows down Direction of an object’s motion changes

Weighing scale

Tsunami

Weight lifting

Ultimate frisbee

Naruto vs Sasuke

Measuring Forces S.I unit of force is newton (N) Spring balance used to measure the amount of force applied

Types of Spring Balance Extension spring balance Spring stretches when a pulling force acts on it Greater force, greater extension Spring attached to a pointer which indicates the amount of force exerted on the spring

Types of Spring Balance Compression spring balance Spring compressed when a pushing force acts on it Greater force, greater compression Spring attached to a pointer which indicates the amount of force exerted on the spring

Forces Around Us Gravity Friction Magnetism

Gravity Gravity is the force that attracts objects to the Earth Mass is a measure of the amount of matter in a body Weight is a measure of the gravitational force exerted on the object

Friction Frictional force acts when one materials rubs against another Friction is useful in walking and when applying brakes to stop a car Constant friction leads to wear and tear Friction produces heat

Magnetism Magnetism is the force exerted by a magnet on magnetic materials such as iron and steel Every magnet has a North pole and a South pole Like poles repel Unlike poles attract

What is Pressure? Amount of force acting on a unit area A sharp object pierces a surface more easily than a blunt object

Calculating Pressure Force Pressure = Area

Applications of Pressure in Everyday Life Bulldozer Can openers Knife Plane Suction cups