1. The Nature of Force and Motion 1.Force – A push or a pull – How strong it is and in what direction? 2.Net Force – The sum of all forces acting on an object. 3.Unbalanced Forces – can cause an object to start moving, stop moving, or change direction. An Unbalanced Force will cause an object to Accelerate (A Net Force > 0). 4.Equal forces – Forces equal in strength, acting in opposite directions. Balanced Forces acting on an object will NOT change the object’s motion (Net Force = 0).

2. The Nature of Force and Motion 5.Inertia – The tendency of an object to resist change in its motion. 6.Mass – The amount of matter in a n object. The SI or metric units used for mass will be the kilogram (kg) or gram (g). 7.Newton’s 1 st law of Motion – An object at rest will remain at rest and an object that is moving at constant velocity will continue moving at constant velocity unless acted upon by an unbalanced force. 8.Velocity – Speed in a given direction. Distance / Time in a given direction

3. The Nature of Force and Motion 9.Acceleration – The rate at which velocity changes over time. Acceleration due to gravity = 9.8m / s 2 10. Speed – Distance covered per unit time – Distance / Time 11.Momentum – Depends on the mass and velocity of an object – Momentum (Kg.m/s) = Mass (kg) x Velocity (m/s)

4. The Nature of Force and Motion 12.Newton’s 2 nd Law of Motion – The net force of an object is equal to the product of its mass and its acceleration. Force [N] = Mass [kg] x Acceleration [m/s 2 ] F = ma 13. Newton – 1 Newton [N] = 1kg x 1 m/s 2 One Newton is the force required to accelerate a 1 kg mass 1 m/s 2.

5. The Nature of Force and Motion 14.Friction – The force that one surface exerts on another when the two surfaces move against each other. Ex. Air Resistance 15.The Nature of Friction – Friction opposes motion. Eventually friction will cause an object to come to a stop. 16.The Strength of Friction – Depends on two things, the types of surfaces involved and how hard the surfaces come into contact with each other. Friction can be both useful and harmful.

6. The Nature of Force and Motion 17.Sliding Friction – Two solid surfaces sliding over each other. Ex. sled over snow 18.Rolling Friction – When an object rolls over a surface. Ex. Bowling ball rolls down the lane 19. Fluid Friction – The friction that occurs when an object moves through a fluid. Ex. The oil in a car engine

7. The Nature of Force and Motion 20. Gravity – The force that pulls objects toward the Earth. Gravity = 9.8 m/s/s =9.8 m/s 2 21. Free Fall – When the only force acting on an object is gravity the object is said to be in free fall. Fall for 10 seconds – Velocity of 98m/s

8. The Nature of Force and Motion 22.Projectile Motion – A ball that is thrown horizontally from a certain height hits the ground at the same time as a ball dropped from the same height.

9. The Nature of Force and Motion 23.Air Resistance & Terminal Velocity – When the fluid friction from the air resistance equals the force of gravity acting on the object, the object has reached terminal velocity. This is the greatest velocity the object can obtain. 24. Weight – The measure of the force of gravity acting on the mass of an object. Weight (N) = Mass (kg) x (9.8 m/s 2 ) 25. Universal Gravitation – The force of gravity acts between all objects in the universe.

10. The Nature of Force and Motion 26.Newton’s 3 rd Law of Motion – If one object exerts a force on another object, then the 2 nd object exerts a force of equal strength in the opposite direction on the 1 st object. 27.Newton’s 3 rd Law of Motion - For every action force there is an equal in strength and opposite in direction reaction force. Ex. A ball hits the wall and bounces back. 28.Momentum – The momentum of an object is equal to the product of the object’s mass and its velocity. Momentum [kg.m/s] = mass [kg] x velocity [m/s]

11. The Nature of Force and Motion 29. Rockets – The rocket can rise into the air because the gases they expel with a downward force exert an equal but opposite force on the rocket. 30.Satellites – An object that travels around another object in space. – Always Accelerating! 31.Centripetal Force – Any force that causes an object to move in a circle.

12. The Nature of Force and Motion 32.The Law of Conservation of Momentum – The total momentum of any group of objects remains the same unless outside forces act on the objects.