What is a Force l A force is

How Do You Measure Force? l The strength of a force is measured in

Combining Forces l more than one force acts on an object l Net Force

Combining Forces Continued… l Forces in same direction – add the forces l Example:

Combining Forces Continued… l Forces in opposite directions – subtract the forces Larger force

Combining Forces Continued… REMEMBER!!! Forces in opposite directions – subtract the forces l Equal

Combining Forces Continued… l There are 2 types of forces: l Unbalanced Forces –

Types of Forces l There are 2 types of forces l Friction – opposes

Friction l Static – between 2 objects that are not moving l Sliding –

Gravity l ALL objects have a gravitational force! l Depends on mass l l

Gravity l Gravity causes ALL objects to accelerate towards the ground at a rate

Gravity l Air resistance – force that acts against gravity l Reason why some

Terminal Velocity l The fastest speed an object can fall l When an object

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What is a Force? l A force is a push or a pull l It is described by: l Strength l Direction in which it acts

How Do You Measure Force? l The strength of a force is measured in Newtons (N) l You exert 1 Newton when you pick up a small lemon l Can you guess what scientist this unit is named after?

Combining Forces l more than one force acts on an object l Net Force – the combination of all forces acting on an object l Determines whether or not an object moves l Determines the direction the object will move

Combining Forces Continued… l Forces in same direction – add the forces l Example: 5 N 5 N = 10 N

Combining Forces Continued… l Forces in opposite directions – subtract the forces Larger force – smaller force = net force l Net force will be in the same direction as the greater force l Example: 5 N 10 N = 5 N

Combining Forces Continued… REMEMBER!!! Forces in opposite directions – subtract the forces l Equal opposing forces will cancel out each other l l Example: 5 N 5 N = 0 N

Combining Forces Continued… l There are 2 types of forces: l Unbalanced Forces – cause change in object’s motion l Can cause an object to start moving, stop moving or change direction l Forces do NOT cancel out – Unbalanced l Balanced Forces – do NOT change an object’s motion l Forces are in equal and opposite directions l Net force is ALWAYS 0

Types of Forces l There are 2 types of forces l Friction – opposes motions of objects when they touch or move past one another l Gravity – acts between any two masses

Friction l Static – between 2 objects that are not moving l Sliding – 2 flat objects move against each other l Rolling – round object moves against flat object l Fluid – solid object moving through a liquid or gas (both are fluids!)

Gravity l ALL objects have a gravitational force! l Depends on mass l l Earth has a larger mass than the moon, so its gravity will be greater than the moon’s Weight – force of gravity on the mass of an object l Your weight on Earth will be greater than your weight on the moon

Gravity l Gravity causes ALL objects to accelerate towards the ground at a rate of 9. 8 m/s 2

Gravity l Air resistance – force that acts against gravity l Reason why some objects seem to fall to the ground faster than others (ex: rock and piece of paper)

Terminal Velocity l The fastest speed an object can fall l When an object falls, the speed increases until it can no longer travel any faster l This occurs due to gravity and air resistance balancing out one another