Motion - a change in position of an object, caused by an object Force – a push or a pull, caused by another object Force Can – Start Motion Stop Motion.

Motion - a change in position of an object, caused by an object

Force – a push or a pull, caused by another object

Force Can – Start Motion Stop Motion Change its direction

There are many different kinds of force. There are pushes

and pulls electromagnetic forces weak forces strong forces and gravitational forces, Some forces are referred to as

contact forces and some are non-contact forces

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Blood flow in the body Plate movement (tectonics)

Volcanic eruptions Earthquakes Mountain building

Emergence of seedlings Erosion

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The net force is the “left over” amount when all the forces are added

(no net force)

If there is a net force, the object will change its direction or velocity. This is called acceleration

Newton’s First Law of Motion – Law of InertiaNewton’s First Law of Motion – Law of Inertia(Was really discovered by Galileo in 1600)

An object will remain at rest or move in a straight line unlessit is acted on by a force.

Force - a push or a pull = Newton (N)

1 Newton = 1 kg x m/s2

Gives ENERGY to an objectContact force - involves objects touching each otherLong range forces - include gravity, magnetism, & electricityInertia - measures an object’s tendency to remain at rest orkeep moving - it is related to mass

Balanced forces - when the forces are equal but in opposite directions, they will cancel each other out. Does not cause motion.

Unbalanced forces - uneven forces acting on an object that did not cancel each other out. The object will move in the direction of the larger one. Cause motion.

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Friction - is a force that resists motion between surfacesthat are touching.

Static Friction - hinders a stationary object from moving on a surface when a force is applied to the object.

Sliding Friction- occurs when two surfaces slides past each other

Rolling Friction - is the force that enables a wheel to roll past on a surface-same direction

Air Resistance - molecules in air colliding with the forward-moving surface of an object, slowing its motion.

An object acted on by an unbalanced force will accelerate in the direction of the force, according to the formula.

Acceleration = Force (Newton) (10N) = 5N/kg or 5m/s2 Mass (Kilogram) (2kg)

Force of Gravity = Force= m x (9.8 m/s2) 9.8m/s2 = acceleration

Mass vs. Weight - Mass is the measure of the amount of matter in an object it remainsthe same.

Weight is a force = mass x (9.8 m/s2) gravity(Mass is a measure of inertia.)

Newton’s Second Law of MotionNewton’s Second Law of Motion

If a 50 kg person in the middle of an ice skating rink pushes a 20 kg box with a force of 10 N, what will the acceleration be?

Acceleration of the box:Acceleration = force

massa = (10 N)

(20 Kg)a = .5m/s2

Acceleration of the person:

Acceleration = force mass

a = (10 N) (50 Kg)

a = .2m/s2

50 Kgperson

20 Kgbox

10 NForce

Weight is the result of the force of gravity pulling on a mass.The greater the force of gravity, the greater the weight.

Mass is a measure of how much matter an object contains.

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Newton’s Third Law of MotionNewton’s Third Law of Motion

For every action, there is an equal,

but opposite reaction. Force always acts in equal and opposite pairs.

(Not the same as balanced forces - different objects.)

When you walk, you push backward

on the ground, and the ground pushes forward on you.

If you put two bar magnets with opposite poles facingone another, they will move toward each other.

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Gravity is a force of attractionbetween objects. The amount of the force depends on themass of each object and the distance between them.

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The earth pulls on the moon while the moon also pulls on the earth.

The earth pulls on other planets and they also pull on the earth

The sun pulls on the earth and moon (and other planets) and the earth and moon pull on the sun

Gravity and the third law -Gravity is pulling you to earth and Earth is also pulled toward you. The same force that keep planets in orbit, is the same force that pulls objects down to Earth. You apply a force to earth, but because earth is more massive than you are, your force has little or no effect. (While F is greater, so is m the mass.)

Newton’s laws apply to all objects, including distant galaxies. Just as the Sun exerts a gravitational force on Earth, Earth exerts an Equal and opposite force on the Sun. This causes a variation in the Sun’s rotation.

Combining the Laws

1.1. You push on the ground, it pushes up on you.

3rd law - equal/opposite reaction

2.2. You leave the ground,you accelerate in the directionof this unbalanced force

2nd law - accelerate in directionof the unbalanced force. 3. When your feet hit the

ground, the ground exerts an upward force on you. When you stop accelerating, all of the forces are balanced.

1st law - you remain at rest.

Combining the Laws1st Law - The canoe will stay until a force moves it. This force comesfrom the push of the puddles.

2nd Law - The canoe changesspeed or direction or both. Thepeople add mass and the paddlers change the canoe’s acceleration by adding a lot of force

3rd Law - The paddlers pushwater backward -an action. Thisbackward force produces an equaland opposite force-a reaction in the water - that move the canoe forward.