What is FORCE? A push or pull on an object Causing resting objects to move Causing moving objects to accelerate
Two Main Force Types Balanced Forces – Two Forces – Opposite directions – Both are equal in value – No movement (stationary) Unbalanced Forces – Two Forces – One greater than the other – Opposite directions – Movement
1 st Law of Motion The Law – Objects at rest remain at rest or objects in motion remain in motion unless acted on by a force AKA – Law of INERTIA
1 st Law of Motion Inertia—force that is resistant to the direction of motion Concept—unbalanced forces Ex: – inertia belts (seat belts) – Space ships going through space
2 nd Law of Motion The Law – The acceleration of a body depends on the ratio of the acting force to the mass of the body Concept – Unbalanced forces AKA – The force formula
Force Formula Force = mass * acceleration F= m*a F= force (unit = Newton) m= mass (unit = kg) a= acceleration (unit m/s 2
Force Example Problems #1 How much force is needed to accelerate a 500-kg car at a rate of 4 m/s/s? #2 A 50-kg object is accelerating at a rate of 2 m/s/s, what is the force that caused this acceleration?
3 rd Law of Motion The Law – For every action there is an equal but opposite reaction Concept – Balanced Forces Ex – Stationary Objects – Rockets being launched
Applying the 3 rd Law If Rico kicked a ball with 100-N of force, how much force did the ball exert on Rico?
What is Friction? Is a force that resist motion and can cause heat Allows us to walk, drive a car, play sports Lubricants help reduce friction
4 Types of Friction Static Friction – Friction force on stationary objects – Ex: book sitting on desk Sliding Friction – Friction acting on objects sliding over a surface – Ex: pushing a box Rolling Friction – Friction acting on objects that are rolling – Ex: car tired Fluid Friction – Friction acting on objects going through a fluid – Fluid—liquid or gas – Ex: swimming or air resistance