Force, Motion, Force, Motion, and Energyand Energy

Newton’s LawsNewton’s Laws

Speed, Velocity, AccelerationSpeed, Velocity, Acceleration

GravityGravity

MotionMotion

Motion occurs when an Motion occurs when an object changes its position.object changes its position. Three Types of Motion:Three Types of Motion:

Relative MotionRelative Motion You v. solar systemYou v. solar system

DistanceDistance How far something movesHow far something moves

DisplacementDisplacement Difference between the end and the startDifference between the end and the start NOT total distanceNOT total distance

SpeedSpeed

Distance traveled per unit of timeDistance traveled per unit of time SpeedSpeed == distancedistance

timetime Example…Example…

You ran 2 km in 10 minutes. You ran 2 km in 10 minutes.

What was your speed?What was your speed?

VelocityVelocitySpeed (a change in position over Speed (a change in position over a period of time), but in a specific a period of time), but in a specific

direction.direction.

Example: Example: The cars at the TexasThe cars at the Texas

Motor Speedway drove a lap. Motor Speedway drove a lap.

They go 120 mph for 60 sec W,120 They go 120 mph for 60 sec W,120 mph for 30 sec S,120 mph for 60 sec mph for 30 sec S,120 mph for 60 sec E, and 120 mph for 30 sec N. They E, and 120 mph for 30 sec N. They had a direction which means they had a direction which means they also had velocity.also had velocity.

AccelerationAcceleration

Acceleration occurs when an Acceleration occurs when an object changes its speed, object changes its speed, direction, or both.direction, or both.

Acceleration = Acceleration = change in velocitychange in velocity

change in timechange in time

When an object changes its When an object changes its direction or speed, it is direction or speed, it is accelerating.accelerating.

ForceForce A force is a push or a pull that A force is a push or a pull that

one object applies to another.one object applies to another. A force can also cause an A force can also cause an

object’s motion to change.object’s motion to change. EX) SportsEX) Sports Balanced forces are equal Balanced forces are equal in size and opposite in in size and opposite in

direction.direction.

InertiaInertia

Inertia is the tendency of an object to Inertia is the tendency of an object to resist any change in its motion. resist any change in its motion.

Objects with more mass have Objects with more mass have

more inertia.more inertia.

Newton’s First LawNewton’s First Law

An object in motion tends to An object in motion tends to stay in motion and an stay in motion and an object at rest tends to stay object at rest tends to stay at rest at rest until acted on by until acted on by an outside force.an outside force.

Force, Mass, AccelerationForce, Mass, Acceleration For any object, the greater the For any object, the greater the

force, the greater the force, the greater the acceleration.acceleration.

The acceleration of any object The acceleration of any object depends on its mass AND the depends on its mass AND the force force

exerted on that object.exerted on that object. KEY CONCEPT: Force, mass, KEY CONCEPT: Force, mass, and acceleration are and acceleration are

connected.connected.

Newton’s 2Newton’s 2ndnd Law of Law of Motion Motion Describes how force, mass, and Describes how force, mass, and

acceleration are connected.acceleration are connected. REMEMBER:REMEMBER:

Net force = total forces acting Net force = total forces acting

on an object.on an object.

States that the net force acting on States that the net force acting on

an object causes the object to an object causes the object to

accelerate in the direction of the accelerate in the direction of the net force.net force.

Newton’s 2Newton’s 2ndnd Law of Law of MotionMotion

Acceleration of an object is determined by the Acceleration of an object is determined by the size of the net force acting on the object and size of the net force acting on the object and the mass of the object.the mass of the object.

So, the relationship between So, the relationship between

acceleration, net force, and acceleration, net force, and

mass can be defined as:mass can be defined as:

F = maF = ma

FrictionFriction If we give a skateboard a push, If we give a skateboard a push,

what happens?what happens? But according to Newton’s 1But according to Newton’s 1stst

Law, what SHOULD happen?Law, what SHOULD happen? REMEMBER:REMEMBER:

When an object slows When an object slows

down, its velocity changes; if its down, its velocity changes; if its

velocity changes, it is accelerating. velocity changes, it is accelerating.

If an object is accelerating, a net If an object is accelerating, a net

force must be acting upon it.force must be acting upon it.

FrictionFriction

The force acting on the skateboard The force acting on the skateboard is friction. Friction is the force that is friction. Friction is the force that opposes motion between 2 opposes motion between 2 surfaces that are touching surfaces that are touching

each other.each other. The amount of friction between The amount of friction between 2 surfaces depends on 2 factors:2 surfaces depends on 2 factors:

The kinds of surfaces.The kinds of surfaces. The force pressing the surfaces The force pressing the surfaces

together.together.

Static FrictionStatic Friction

What does “static” mean?What does “static” mean? Applied force is equal to the friction Applied force is equal to the friction

between the two surfaces.between the two surfaces.

Sliding FrictionSliding Friction

Applied force is greater than the friction Applied force is greater than the friction between the two surfaces.between the two surfaces.

Rolling FrictionRolling Friction

The friction between a rolling The friction between a rolling object and the surface it rolls object and the surface it rolls on.on.

Rolling friction is usually Rolling friction is usually much less than static or much less than static or sliding friction.sliding friction.

That is why it is easier to pull That is why it is easier to pull a load in a wagon rather than a load in a wagon rather than dragging it along the ground.dragging it along the ground.

Friction FoldableFriction FoldableTermTerm Definition/Definition/

ExampleExample

PicturePicture

FrictionFriction

Static FrictionStatic Friction

Sliding FrictionSliding Friction

Rolling FrictionRolling Friction

Newton’s Third LawNewton’s Third Law

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

Examples:Examples: TrampolineTrampoline Rocket PropulsionRocket Propulsion