1. Soles of shoes and tires of cars wearing out, causes objects to lose energy through heat
2. Frictional, Gravitational and Magnetic Force
2.1. The weight of an object depends on the force of gravity pulling on it; the greater the force of gravity pulling on it, the heavier it is
2.2. Friction occurs when two moving surfaces are in contact. Friction slows down and stops a moving object. Friction allows us to do many things such as walking and unscrewing a cap off a bottle
2.3. Magnets exert magnetic force, which attracts and repels other magnets and attracts magnetic materials. Magnetic force is also used in transportation, such as the maglev train
2.4. Frictional Force is NOT dependent on surface area of contact but on the total mass
3. It is a push or a pull
4. Effects of a Force
4.1. 1. Stop a moving object
4.2. 2. Change direction of a moving object
4.3. 3. Change shape of an object
4.4. 4. Speed up / Slow down a moving object
5. Measured using a spring balance
5.1. The force on the spring is proportional to the extension of the spring
5.2. When there is no weight on the spring, the length of the spring is its original length. The length is NOT zero!
