Force = a push or a pull Mrs. Clarici Force is described by - its strength measured in newtons (N) - the direction in which it acts using vectors (arrows) Net force = total force Balanced force net force = 0 N does not change object’s motion Unbalanced force causes a change in the object’s motion

Friction Mrs.Clarici force that two forces exert on each other when they rub against each other Strength depends on - how hard they are pushed together less more - surface type Friction types: 1. Static friction acts on non-moving objects 2. Sliding friction - two solids slide over each other 3. Rolling friction - rolls across a surface - less resistance 4. Fluid friction - solid moves through a solid ex. air resistance- least resistance

Newton’s Law of Universal Gravitation Mrs Newton’s Law of Universal Gravitation Mrs. Clarici Gravity = force that pulls objects towards each other Factors affecting gravitational force 1. Mass = amount of matter in an object more mass = more gravity 2. Distance between objects more distance = less gravity Mass = amount of matter grams (g) mass does not change Mass vs. Weight: Weight = force of gravity on an object on a planet newton (N) or pound (lb) weight can vary

Gravity and Motion Mrs. Clarici Free fall - the only force acting on an object is gravity Projectile Motion - thrown object Two forces = horizontal push and gravity Terminal velocity object continues to fall, but its velocity remains constant -no acceleration - reached when force of air resistance = weight of the object

Newton’s First Law of Motion Mrs Newton’s First Law of Motion Mrs. Clarici - an object at rest will remain at rest - an object moving at a constant velocity will continue moving at a constant velocity unless it is acted upon by an unbalanced force - aka inertia = resistance to a change in motion inertia depends on mass

Newton’s Second Law of Motion Mrs Newton’s Second Law of Motion Mrs. Clarici Acceleration depends on object’s mass and net force acting on the object. acceleration = net force mass force = m x a

Newton’s Third Law of Motion Mrs Newton’s Third Law of Motion Mrs. Clarici If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. or For every action there is an equal but opposite reaction.

Momentum = mass x velocity Mrs Momentum = mass x velocity Mrs. Clarici Quantity of motion Law of Conservation of Motion Total momentum of any group of objects remains the same (conserved), unless outside forces act on objects. Newton’s cradle

Satellite = any object that orbits another object in space Mrs Satellite = any object that orbits another object in space Mrs. Clarici Satellites in orbit around Earth continuously fall toward Earth, but because Earth is curved, they travel around it. Centripetal force = any force that causes an object to move in a circular path “centripetal” = center seeking