FORCES Outcome 4.6 Stage 4

overview 1) What is a force? Examples of forces Measuring forces 2) Contact forces 3) Non-contact forces 4) Balanced Forces 5) Unbalanced Forces This symbol means that there is a question on your worksheet to be filled in! It will appear in this corner so you don’t miss anything!

what is a force? Nothing moves by itself. Objects must be pushed or pulled! …or a… A force is a…

We use forces every day! ActionPush and/or Pull? Pressing a button Climbing a tree Jumping Walking Towing a car Jumping PUSH PULL PUSH PULL PUSH PUSH & PULL PULL PUSH

What changes happen when forces are applied? Changing the speed of an object Changing the shape of an object Stopping a moving object Changing the direction of an object Moving a stationary object

Forces are measured in Newtons, written as N for short How do we measure a force? %20and%20Motion%20WebQuest/force%20meter.gif Forces are measured using a Force Meter, which uses a spring The bigger the force, the more the spring stretches Or, we can calculate it using this equation: Force = mass x acceleration

Forces can happen between objects………... …or from a distance non-contact (non-contact forces): 1)Electrostatic force 2) Magnetic force 3) Gravitational force …by touching contact (contact forces): Frictional force

Forces normally occur in pairs……… These pairs are called Action and Reaction The Action force causes a change Example: car tyres push backwards on the road to move the car forwards The Reaction force is the force that ‘reacts’ to the action force. Example: the road pushes forward against the cars tyres

Forces normally occur in pairs……… Action and Reaction forces act in OPPOSITE directions They can be BALANCED or they can be UNBALANCED