Topic 3 - Forces

• Forces are push or pulls
• Forces can: change the size or shape of an object, change the speed an object goes, change the direction of a moving object
• Units for force = Newtons ( N )
• Contact forces = friction, air resistance, water resistance, upthrust
• Non-contact forces: Magnetism, gravity, static electricity
• Mass units = Kilograms ( kg ) usually
• Mass: The amount of matter in an object or substance.
• Weight is measured by Newton's (N)
• Extension ( of a spring ) = difference between original length and stretched length
• Hooke's law = extension is directly proportional to the force on it
• Bigger force = Bigger pressure
• Friction can: produce heat, make a sound, slow things down, wear things away
• Balanced forces VS unbalanced forces