Motion And ForcesMotion And ForcesSC-05-1.2.1 & SC-06-SC-05-1.2.1 & SC-06-

1.2.11.2.1

May the force be with you!May the force be with you!

Mass vs. WeightMass vs. Weight

Mass is the amount of “stuff” in an object, Mass is the amount of “stuff” in an object, or the measure of inertia of an object.or the measure of inertia of an object.

Weight is the pull of gravity on an object.Weight is the pull of gravity on an object.– An object’s mass is the same throughout the An object’s mass is the same throughout the

Universe, but your weight changes depending Universe, but your weight changes depending on what planet your on.on what planet your on.

– Because the gravitational pull on Mars is less Because the gravitational pull on Mars is less than Earth, you than Earth, you weighweigh less on Mars, but your less on Mars, but your massmass is the same at both locations. is the same at both locations.

MotionMotion

Motion is the change in Motion is the change in position of an object, position of an object, measured by distance and measured by distance and time.time.

ForceForce

A force is any push or pull on A force is any push or pull on an object.an object.– Forces give energy to objects.Forces give energy to objects.– Forces cause a change in the Forces cause a change in the

motion of an object.motion of an object.

Frame of referenceFrame of reference

The point from which movement is The point from which movement is determined.determined.– To measure movement, some point To measure movement, some point

must be considered as nonmoving.must be considered as nonmoving.– Earth is the most common frame of Earth is the most common frame of

reference.reference.

SpeedSpeed

The distance traveled by a moving The distance traveled by a moving object per unit of time.object per unit of time.– To calculate speed, use the equation: To calculate speed, use the equation:

Speed = distance/timeSpeed = distance/time

- Speed only gives distance and time.- Speed only gives distance and time.

Average SpeedAverage Speed

The speed of a moving object is not The speed of a moving object is not always constantalways constant

Average speed = total distance/total Average speed = total distance/total timetime

VelocityVelocity

Velocity is the speed of an object in a Velocity is the speed of an object in a given direction.given direction.– Velocity gives distance, time and the Velocity gives distance, time and the

direction of travel.direction of travel.

AccelerationAcceleration

Is the change of speed over time.Is the change of speed over time.

Deceleration occurs when the Deceleration occurs when the change in speed, or acceleration, is change in speed, or acceleration, is in the negative direction.in the negative direction.– Commonly used to mean a decrease in Commonly used to mean a decrease in

speed.speed.

Sir Isaac NewtonSir Isaac Newton

An English mathematician and An English mathematician and physicist who discovered one of the physicist who discovered one of the most important relationships in most important relationships in physics: the relationship between the physics: the relationship between the force on an object, its mass, and its force on an object, its mass, and its acceleration.acceleration.

Newton’s First Law of Newton’s First Law of MotionMotion

An object will stay at rest, while an An object will stay at rest, while an object in motion will stay in motion, object in motion will stay in motion, unless acted upon by an unbalanced unless acted upon by an unbalanced force.force.

* In other words, unless you apply a * In other words, unless you apply a force to an object, it tends to keep force to an object, it tends to keep doing what it was doing in the first doing what it was doing in the first place.place.

InertiaInertia

Newton was the first to use the term Newton was the first to use the term inertiainertia to describe the tendency of to describe the tendency of object to remain in motion or stay at object to remain in motion or stay at rest. Inertia comes from the Latin rest. Inertia comes from the Latin word word inersiners, which means lazy., which means lazy.

Newton’s Second Law of Newton’s Second Law of MotionMotion

The acceleration of an object is The acceleration of an object is directly related to the force acting on directly related to the force acting on it and inversely related to the it and inversely related to the object’s mass.object’s mass.

Force = mass x accelerationForce = mass x acceleration

– In other words, force causes an object to In other words, force causes an object to accelerate, while the object’s mass accelerate, while the object’s mass resists acceleration.resists acceleration.

Newton’s Third Law of Newton’s Third Law of MotionMotion

For every action, there is an equal For every action, there is an equal but opposite reaction.but opposite reaction.

In other words, all forces act in pairs In other words, all forces act in pairs

FrictionFriction

Friction is a force that opposes Friction is a force that opposes motion.motion.– Friction always works against the motion Friction always works against the motion

that produces them.that produces them.

– There are 3 types of friction:There are 3 types of friction: Fluid FrictionFluid Friction Sliding FrictionSliding Friction Rolling FrictionRolling Friction