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Honors Physics Semester 1 Review PowerPoint. Distance vs Displacement. 0 1 2 3 4 5 6 7 8 9 . Distance = magnitude only = 8m. Displacement = magnitude and direction = Δ x = x 2 – x 1. Δ x = x 2 – x 1 = 9m – 1m = +8m. Acceleration. - PowerPoint PPT Presentation

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Honors Physics Semester 1 Review PowerPointDistance vs Displacement

0 1 2 3 4 5 6 7 8 9 Distance = magnitude only = 8mDisplacement = magnitude and direction = x = x2 x1 x = x2 x1 = 9m 1m = +8mAccelerationWhen you increase your speed in a car, are you accelerating?When you turn in a car, are you accelerating?When you slow down in a car, are you accelerating?This is called deceleration or negative acceleration or acceleration in the direction opposite of the cars movement.

3Objectives: define distance and calculate speed, and explain what is meant by scalar quantity.

Scalar Quantity:Quantity with only a numerical valueDistance tells us how far but not in what direction.TimeMassTemperature

Graphical AnalysisZero accelerationPositive acceleration

KinematicsSpeed: the rate at which distance is traveled

Constant Speed: speed of object does not change

Average speed = total distance/total time

Units: meters m second sREVIEW:Motion: change of positionScalar: numbers onlyVector: directionVelocity: change of speed in a given directionAcceleration: a change in velocity

Therefore, a change in speed or a change in direction

GraphsPosition v Time graphs

constant velocity v = acceleration

8Speed and VelocityThere are two types of Velocity:1. Average Velocity V = d/t

For example, when a car moved 50 km in 2 hours, the average velocity is 25km/h.

2. Instantaneous VelocityFor example, when the speed cameras give you a ticket, they show the car driving at 90 km/h for that instant.

9VelocityWhat is the velocity of this object between 0-4 sec?What is the initial starting position of the object?What is the displacement of this object from 3-4 seconds?What is the objects final position?

Position in Meters10GraphsAssuming the objects motion does not change, what would its position be at t=20s?

Time (seconds)Position in Meters11What is happening to the velocity of these two objects?What is happening at t=2s?At t=4s, which object has greater speed?

Graphical AnalysisZero accelerationPositive acceleration

Newtons First Law of Motion or Law of Inertia: in the absence of an unbalanced force, a body at rest remains at rest, and a body in motion remains in motion with a constant velocity (speed and direction).

Inertia and Newtons 1st LawInertia - tendency of an object to overcome a change in motionCharacteristics: more mass = more inertia

Mass is the quantitative measure of inertia.

Net Forces

Normal ForceWhen an object is sitting on a level surface then the normal force is always equal and opposite of the weight of the object.

Forces SymbolsFapp applied force (push or pull)Fg force of gravity (always toward center of earth or down)Fn normal force (always perpendicular to surface)Ff force of friction (same as surface)

Balanced forces do not change the objects motion.

FORCESUnbalanced forces result in a change in the objects motion.

Newtons First Law of Motion or Law of Inertia: in the absence of an unbalanced force, a body at rest remains at rest, and a body in motion remains in motion with a constant velocity (speed and direction).

Newtons 3rd Law of MotionFor every force (action), there is an equal and opposite force (reaction).

Free Fall Force of Gravity ONLYFree Fall: A Particular Acceleration

How fast a falling object moves is entirely DIFFERENT from how far it moves.

We will treat x and y separately

2323SI Unit: Newton = kg m/s2

Force is a vector (magnitude/direction)

Like velocity and acceleration, force has a strength AND a direction

FORCEResultant Force: the total of all forces acting on an object.

Force 1 pushes upward with 2 NForce 2 pushes horizontally with 5 N

25Net Forces with angles

Net Forces with anglesWhat is the net force on this object?

What is Fs?What is FN?

Pull Force of20 N at 1650kgTypes of FrictionStatic Friction:Frictional force is sufficient to prevent motion between surfaces.

Static Friction Formulafs sN (static conditions = no movement)

scoefficient of static frictionFriction (think about ice)

Normal ForceNormal means perpendicular.Force that a surface exerts on an object.Normal ForceWhen an object is sitting on a level surface then the normal force is always equal and opposite of the weight of the object.

Force FormulaAcceleration of an object is directly proportional to the net force and inversely proportional to its mass.

Acceleration = Force Mass

Momentum and ImpulseThe concept of impulse and momentum using Newtons 2nd Law: F = ma a = vf vi = vF = m v t t tTake t to the other side:

Impulse-Momentum Theorum = F t = m v

F(t) is called IMPULSE. It is defined as a force acting through time.Impulse is numerically equal to the of momentum. So a force acting for time on some object gives rise to a change of the objects momentum. Is momentum conserved?YES.The momentum lost by one object is gained by the other object.The total amount is constant.

Elastic CollisionsTotal Kinetic Energy is conservedFollows the Law of Conservation of Momentum

Kafter = Kbefore

Inelastic CollisionsKinetic energy is NOT conserved

Change in original shapesSound and friction KE lost

Linear MomentumFormula: = m v = momentumm = massv = velocitySI Units?kg m/s

Law of Conservation of Linear Momentum:"the total momentum of an isolated system of interacting bodies remains constant."

OR

"Total momentum of an isolated system before collision is always equal to total momentum after collision.

Correlates to Newtons 1st Law of MotionRadiansCorrect SI unit for angular measurements

1 rad = 360/2 = 57.3

Calculators: switch to rad when told

Period and FrequencyFrequency: number of cycles per unit of time. f = 1/t or s-1Period: (t) time it takes an object in circular motion to complete one revolution or cyclet = 1/fFrequency and period = inverse relationshipFrequency SI: 1/s = Hertz (Hz)

Heinrich Rudolf Hertz Uniform Circular MotionNeeds 3 things1. Centripetal Force

Uniform Circular Motion2. Angular Acceleration3. Constant Speed

V=Tangential velocitywants to go in a straight line

Gravitational Field Lines for Two Objects

Keplers 3rd Law of Planetary MotionThis Law lets us determine a newly discovered planets distance from the Sun.

Keplers Laws of Planetary MotionKeplers 2nd Law: (Law of Areas)A line from the Sun to a planet sweeps out equal areas in equal lengths of time.

46Escape VelocityWhat kind of energy must a man-made satellite have to escape Earths gravitational pull?

Formula for Escape Velocity:

Escape speed = escape surface of Earth is about 11km/s or 7mi/s

Centrifugal is just Inertia what Law?Newtons 1st: an object in motion wants to stay in that motion and not change speed or direction unless acted upon by an outside force.