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## 2011 Physics Study Guide

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**2011 Physics Study Guide**By: Steph Rizzi**Measrument/Units**• Scientific Notation: • -notation tool used for extreme magnitudes Examples: 1. 46600000 = 4.66 x 107 2. 0.00053 = 5.3 x 10-4 • Metric Prefixes: • A notation tool for measurements utilizing powers of ten**One-dimensional Motion**• Displacement: • “Change in position” • Not the same as distance traveled • Notation= • = f-I • Final position minus initial position**Velocity**• Velocity (v): • “Change in position over change in time” • Not the same as speed • Two basic velocities: • Average • Instantaneous (initial and final) • Units of velocity: meters per second (m/s) • Velocity has a direction • Equation:**Acceleration**• Acceleration (a) • “change in velocity over change in time” • Acceleration has a direction- it can be positive or negative • Negative acceleration means you are slowing down • Equation**Graphical Display of MotionAcceleration Vs. Time***horizontal lines have a slope of zero**Free-Fall Motion**• Any motion of a body where gravity is the only or dominant force acting upon it, at least initially • Things that affect free fall • Air resistance • Elevation • Where you are in the universe • Tips, Tricks, and Hints for Free Fall • “same height” or “original position” • 1. • 2. Vi= -Vf • 3. Vtop=0 m/s • G= 9.8 m/s2**Two-Dimensional Motion**• 2 dimensional motion is really just tow 1D motion equations • Now have Y= vertical displacement**Scalars vs. Vectors**• Scalar- just a magnitude (amount) • Vector- includes a magnitude AND a direction**Vector Addition**• Finding the resultant vector (sum/final) • Colinear- in a line • *Add vectors “head to tail”**Relative Motion**Always true: Ay= -9.8 m/s2 Vix=Vfx t is always positive Ax= 0 m/s2**Paths of a Projectile**• Projectile- • An object falling over a distance above the surface of a massive body • “free falling with a horizontal velocity” • Projectiles follow a parabolic path**Force and Motion**• Newton’s Laws: • 1. an object in motion or at rest will remain in motion or at rest, unless acted upon by an outside force • 2. F= ma, force is equal to mass times acceleration • 3. For every action force, there is an equal and opposite reaction force**Inertia**• “The tendency of all mass to maintain its state of motion” • When mass increases, so does inertia • Equilibrium • Fnet (total)= N • Constant speed only means equilibrium if its in a straight line= constant velocity= no acceleration= no force • Gravity • Law of universal Gravitation**Forces**• Friction: • A force that resists motion of one object over (or through) another object • Two types: • 1. Static Friction- force of friction between two surfaces at rest relative to one another • 2. force of friction between two surfaces in motion relative to one another**Normal Force**• “perpendicular force” • Always perpendicular to the surface • Always matches the force exerted perpendicular to the surface unless the max normal force is reached in which case the surfaces will falter**Net Force Problems**• Steps To Solve: • 1. Draw a diagram • Forces on a “free body” • 2. Final all x and y compononents • 3. Find Fnetx and Fnety • Add all x’s together to get Fnetx • Add all y’s to get Fnety • 4. Create a right triangle • 5. Calculate Fnet magnitude and the angle using SOH CAH TOA**Momentum and Impulse**• Momentum (p) • Has a direction because it is a vector**Real World Examples**• Parachuting • Football helmet padding • Something hitting water • Airbag**Conservation of Momentum**• Momentum is conserved for interactions between two objects in a closed system**Work and Energy**• Work: W= Fd • In units of joules**Solving a Work Problem**• There is a specific work for every force of an object • This includes Wnet= FnetX • Only one object= one X**Conservation of Mechanical Energy**• According to the law of conservation of mechanical energy, in an isolated system, that is, in the absence of non-conservative forces like friction, the initial total energy of the system equals to the total energy of the system. Simply stated, the total mechanical energy of a system is always constant (in case of absence of non-conservative forces). For instance, if a ball is rolled down a frictionless roller coaster, the initial and final energies remain constant. Conservative forces are those that don't depend on the path taken by an object. For example, gravity, spring and electrical forces are examples of mechanical energy • Mechanical Advantage • Work in = Work out • No units • Usually a decimal or a percent**Types of Energy**• Energy is the ability to do work • Potential energy • Stored energy • Gravitational PE- energy stored in an object at a height above a gravitational source (earth) • PE= mgh (J) • Elastic PE- energy stored in a compressed or stretched spring • PEe= ½ KX2 (J)**Circular Motion**• t for 1 revolution is called a period • T= the amount of time for one revolution in seconds • Centripetal Acceleration • Centripetal force- the force that causes circular motion by pushing or pulling an object towards the center