1. FORCES CH. 2

2. What is a Force? Def: a push or a pull –Measured in Newtons Kg · m/s 2 –Balanced Force – an equal but opposite force acting on an object. Net force is 0 Does not cause a change in motion –Unbalanced force causes a change in motion –Newton’s 3 Laws of Motion Law of Inertia F = MA Action- Reaction

3. Examples of Forces Friction – force that opposes motion –Sliding, rolling or fluid (gas or liquid) Air Resistance – fluid friction of objects moving through air Lubricant – a fluid that reduces friction –Static Friction – friction between two objects that are not moving –Friction is good and bad Good:Bad:

4. Examples of Forces Gravity – pulling force between objects –Law of universal gravitation – all objects in the universe exert a gravitational pull on all other objects in the universe Size of the gravitational pull depends on mass and distance –larger the mass; greater the force of gravity –Greater the distance between the objects; gravity is less

5. Examples of Forces –Acceleration due to Gravity – the rate at which falling objects accelerate Same for all objects, regardless of mass, size or shape –This is without any other forces (air resistance) –Earth = 9.8 m/s 2 ; Moon = 1.6 m/s 2 Terminal Velocity – fastest an object can fall because of air resistance –Air resistance = Force of Gravity –Weight – measure of the force of gravity on an object Mass X acc. Due to gravity