2. Force<br />Force is simply a push or a pull.<br />The Newton is the unit used to express force.<br />When you pull a stuck door, you are applying more force to the door.<br />
3. Forces Act on Objects<br />A force is always exerted by an object and always acts on another object.<br />
4. Net Force<br />Net force is the result from combining all the force exerted on an object.<br />
5. Net Force<br />A net force acting on a stationary object will move the object.<br />
6. Force<br />Forces come in pairs<br />Forces have a magnitude and a direction<br />Magnitude: 5N<br />Direction: north (up)<br />5N, north (up)<br />
7. Balanced and Unbalanced Forces<br />Forces occur in pairs and they can be either balanced or unbalanced <br />
8. Balanced Forces<br />A stationary object will not move while the forces acting on it are balanced.<br />
9. Balanced Forces<br />Balanced forces do not cause change in motion<br />They are equal in size and opposite in direction<br />
10. Unbalanced Forces<br />When the net force of an object is not zero, the forces on the object are unbalanced.<br />An unbalanced force always causes a change in motion<br />
11. Unbalanced Forces<br />3 N, right – 6 N, left = 3N, left<br />
12. Unbalanced Forces<br />4 N, left – 10 N, right =<br />6N, right<br />
13. Newton’s Second Law of Motion<br />Force = mass X acceleration<br />F = ma<br />Force and acceleration are directly proportional. The greater the force, the greater the acceleration.<br />Mass and acceleration are inversely related. The greater the mass of an object the less the acceleration if the same force is applied.<br />
14. What is friction?<br />Friction is a force which opposes motion.<br />Friction is an important force in our lives. We rely on friction in many ways. An athlete usually wears shoes which provide him or her with a greater friction between the shoe and the surface. We rely on friction as an important aspect of our motion. In what other ways does friction play a role in our everyday lives?<br />
15. Air Resistance – another type of friction??<br />Air resistance is a force which opposes a moving object. This can be easily seen with falling objects. When a piece of paper and a crumple piece of the same type of paper are dropped, they fall at the same rate.<br />A penny and a feather dropped in air will not fall at the same rate, but a penny and feather dropped in a vacuum (no air) will.<br />
16. What is Gravity?<br />Gravity is a force of attraction between two objects.<br />Law of Gravitation – any two masses exert an attractive force on each other. The amount of attraction depends upon two things: the mass of the objects and the distance between the objects.<br />