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2011 PHYSICS STUDY GUIDEBy: Steph Rizzi
MEASRUMENT/UNITS
Scientific Notation: -notation tool used for extreme magnitudesExamples: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
PREFIXES
Prefix Symbol Power x10
Centi- C -2
Milli- M -3
Kilo- K 3
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 MOTIONDISTANCE VS. TIME
GRAPHICAL DISPLAY OF MOTIONVELOCITY VS. TIME
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
Scalar Vector
Temperature Force
Mass Weight
Speed Displacement
Distance Velocity
Area Acceleration
Volume Pressure
Time
Power
Heat
Vector Addition Finding the resultant vector (sum/final)
Colinear- in a line *Add vectors “head to tail”
RELATIVE MOTIONName Diagram Inferred
givensNotes
Launched horizontally from a height
Vix=Vi
Viy=0 m/sY is negative
Launched from an angle to the same height
Y= 0mVix=Vfx
Ax= 0 m/s2
Vfy= -Viy
Vfytop= 0 m/sttop= t/2
Use SOH CAH TOAVix= Vi cosθViy=Visinθ
Launched at an angle from a height
Y= 0mVix=Vfx
Ax= 0 m/s2
Vfy= -ViyVfytop= 0 m/sttop= t/2
Y is negativeFind Vfy to find t
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
INCLINE
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
Name Diagram Notes
Inelastic -sound-energy is lost-most common
Perfectly inelastic -energy is lost-sound-real-world
Elastic -energy is conserved-no sound-not real-world (ideal)
WORK AND ENERGY
Work: W= Fd In units of joules
Situations
Force in the same direction as X
Positive work
Force in the opposite direction as X
Negative work
Force is perpendicular No work
Object is at rest No work
SOLVING A WORK PROBLEM
There is a specific work for every force of an object
This includes Wnet= FnetX Only one object= one X
KINETIC ENERGY
MECHANICAL ENERGIES
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
TORQUE
ROTATIONAL EQUILIBRIUM