Week+2

=Day 6=

toc

**Lesson 11**
__**In Class**__


 * **Projectile**
 * An object shot horizontal will fall at the same rate as one that falls straight down.
 * An object shot upwards at an angle goes up till it hits the maximum height then it falls.
 * Must have only a force of gravity acting on it
 * Must have a horizontal velocity.
 * Information needed to solve for velocity
 * Time
 * Initial information
 * Accelerations
 * To solve use kinematics
 * v final =v initial +at

__**At Home**__

**Projectile Motion**


 * What (specifically) did you read that you already understood well from our class discussion? Describe at least 2 items fully.
 * For any free falling body to be a projectile, the only force acting on it is gravity. Though inertia causes an object not to change direction, gravity changes causing an object that is going over a cliff to fall.
 * An object travels at a constant horizontal velocity and a downwards vertical acceleration. So the speed of the ball downward is the same as a ball that is dropped. At a non horizontal launch, the object will go upwards till it decelerates to a velocity of zero then falls.
 * The movement of a projectile is determined by the speed of the object and if it is going at an angle. If the object is at an angle, then the speed of the object is split between the horizontal velocity and vertical velocity.
 * What (specifically) did you read that you were a little confused/unclear/shaky about from class, but the reading helped to clarify? Describe the misconception you were having as well as your new understanding.
 * There was no misunderstandings.
 * What (specifically) did you read that you still don’t understand? Please word these in the form of a question.
 * I understand everything.
 * What (specifically) did you read that was not gone over during class today?
 * Everything was covered in class.

Clip: Does a shot bullet really fall at the same rate as a dropped bullet? Find out [|here.]



**Lesson 12**
__** In Class **__


 * ** Lab **
 * Data
 * [[image:a3.JPG width="800" height="112"]]
 * [[file:Lab 6.xlsx]]
 * Calculations
 * To find the time for experimental velocity
 * d y ﻿=v i ﻿t+(1/2)at^2
 * .777=0t+(1/2)(9.8)t^2
 * .777=4.9t^2
 * .1586=t^2
 * t=.398 (s)
 * To find velocity
 * v i ﻿=m/s
 * v i ﻿=.427/.398
 * v i = 1.073 (m/s)
 * To find distance of drop zone
 * d x ﻿=v ix ﻿t+(1/2)at^2
 * d x ﻿=1.09(.398)+(1/2)*(0)*(.398)^2
 * The experimental velocity is used
 * d x ﻿=.434 (m)
 * Class average for experimental time
 * (.95+1.01+1.05+1.09)/4
 * 1.025 (m/s)
 * Class average for theoretical time
 * (1.05+1.11+1.03+1.11)/4
 * 1.075 (m/s)
 * Percent difference
 * Experimental
 * abs(1.09-1.025)/1.025*100%
 * .0063*100%
 * .6% difference
 * Theoretical
 * abs(1.03-1.075)/1.075*100%
 * .041*100%
 * 4.1% difference
 * Analysis
 * The x and y axis are independent so the force of gravity did not affect the speed of the ball moving horizontally.
 * The percent difference being so small in the first one shows that people had the same problems with calculating the speed, such as getting the right time and distance. The second percent difference is due to the gate being held slightly different from group to group and different measurements for distance.

__** At Home **__ = = =Day 7=

** Lesson 13 **
__** In Class **__


 * Lab **


 * Objective: What is the relationship between acceleration and the angle of incline.
 * Hypothesis: As the incline gets steeper the acceleration
 * Reasoning: As the incline gets steeper the force of gravity acting on the ball's x axis gets greater.
 * Data:
 * [[file:Lab7.xlsx]]
 * [[image:a4.JPG width="800" height="83"]]
 * Graph
 * [[image:a5.JPG]]
 * Analysis
 * As the slope gets steeper, there is a clear increase in time. The slope should 9.8 and there should be no y intercept. The percent error is 68.5%. The error is due to human error. The reaction time caused to be off. To correct this the person releasing the car should also start the timer. Another source of error is that the person releasing the cart may be pulling the car back when releasing it. The Way to fix this is by having less contact with the cart before releasing the cart. The biggest reason for the large error is that this is mall scale meaning any slight error will cause a great amount error to show up, it would be better to do this on a large scale.

__** At Home **__


 * ** Forces in two Dimensions **
 * Any object that has any forces applied on it and has no acceleration then the forces added together equals zero. The vectors of the force when put at top to end return to the same point.
 * All forces that are not on the x or y axis can be split into x and y forces. This concept allows a sail boat to travel up wind.
 * An object in equilibrium has a net force of zero. The vectors of that object when split into their x and y components and are added up, the net force along both the y and x axis is zero.
 * An object on an incline must have its weight vector separated in to two different vectors. One vector is along the x axis that is pointing down the incline. The other is along the y incline witch equals the Normal force.

[|Video] of using an incline for something else.



** Lesson 14 **

 * In Class **


 * ** Law of Universal Gravitation **
 * Every object is gravitational attracted to every other object
 * Objects are not attached because the forces of gravitation of an object is too small to count compared to the earth.
 * Gravitational force is proportional to the product of the masses.
 * Gravitational force is inversely proportional to the square of the distance.
 * Distance is the center of one object to the center of the other object
 * Radii of some objects may be negligible
 * ** Constant **
 * Universal gravitational constant
 * Symbol G
 * F g =G(m 1 *m 2 )/(d*d)
 * Simple experiment to find a very important constant
 * G=6.67 x 10-11 Nm2/kg2
 * w=mg can only be used on earth
 * g changes as distance from the earth changes
 * ** Kepler's laws **
 * Law of Ellipses
 * Planets move in elliptical orbits around sun with the sun at one focus. Eccentricity is how far from a circle the orbit is.
 * Law of Equal Areas
 * The area between the two point is equal to the area of another area between two points if the time elapsed is the same.
 * The closer to the sun, the faster you are moving
 * Law of Harmonies
 * The period squared over the radius from the sun cubed is the constant that is the same for all planets in our solar system

__** At Home **__


 * ** Universal Gravitation **
 * Gravity is more than just saying what goes up comes down. Gravity is a force that causes all objects to accelerate to one another.
 * Kepler has three laws that only work in our solar system. The Law of Ellipses that states the paths of the planets about the sun are elliptical in shape, with the center of the sun being located at one focus. The Law of Equal Areas that states an imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. The Law of Harmonies that states that the ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun.
 * Newton discovered that the force of gravity changes. He found that the force of gravity is inversely proportional to the distances from the center of the objects. He also found that the product of the two masses where proportional. Later this lead Henry Cavendish to discover the universal constant and put it all together.
 * [[image:http://www.physicsclassroom.com/Class/circles/u6l3c3.gif]]

A nice little [|video] on gravitational pull.



=**Day 8**=

**Lesson 15**
__** In Class **__


 * **Circular motion**
 * Changing velocity
 * Changing speed
 * Changing direction
 * Uniform Circular Motion
 * Constant speed
 * Changing direction
 * No kinematic equation
 * Centripetal forces at work
 * Caused By normal force
 * **Lab**




 * Data
 * [[image:a9.JPG width="800" height="50"]]
 * Calculation
 * To Find Circumference
 * c=2*pi*r
 * c=2*3.14159*.5
 * c= 3.14159 (m)
 * To find Period
 * p=t/#of rev.
 * p=18/20.3
 * p= .88 (s)
 * To find max tension
 * t=gm
 * t=9.8*.92
 * t= 9.016 (N)
 * To find Experimental velocity
 * v=c/p
 * v=3.14159/.88
 * v=3.559 (m/s)
 * To find theoretical value on top of circle
 * w=(m*v^2)/r
 * .01*9.8=(.01*v^2)/.5
 * 9.8=(v^2)/.5
 * 4.9=v^2
 * v=2.21 (m/s)
 * To find theoretical value at the bottom
 * t-w=(m*v^2)/r
 * 9.016-(.01*9.8)=(.01*v^2)/.5
 * 8.92=(.01*v^2)/.05
 * 44.6=v^2
 * v=21.1 (m/s)
 * Percent Error
 * abs(v e -v ﻿t )/v t *100%
 * abs(3.56-2.21)/2.21*100%
 * 1.35/2.21*100%
 * .6077*100%
 * 60.77%
 * Analysis
 * The large percent error is due to human error. The person swig the object might not have the speed going at a constant rate and the speed most likely was not the minimal speed needed. The timing was off because the timer needed better reaction for maximum speed for when the string snapped. The weight was moving to fast for the person to see and might not have been counted correctly for the number of revolutions. The time to revolution could also be off since the string most likely snapped in a place where it did not complete a full revolution yet.

At Home

>>> >>> >>> >>>  Yep, another [|video].
 * Motion Characteristics for Circular Motion
 * How do you find the speed of an object moving in a circle?
 * The average speed is equal to the circumference over the time.
 * R stands for radius and T for time.
 * What is the vector of an object in a circular motion?
 * The vector is tangent to the circle with the object at any given point, as the start of it.
 * Is there an acceleration if an object has constant speed?
 * If an object has constant speed, but changes direction then yes, it is accelerating.
 * What is centripetal force?
 * The force is what keeps an object circling a center point.
 * There is always a inward net force for the object moving in a circle.
 * What is centrifugal?
 * It means the an outwards force.
 * It does not exist.
 * How do you calculate acceleration
 * [[image:http://www.physicsclassroom.com/Class/circles/u6l1e2.gif]]



**Lesson 16**
__**In Class**__


 * **Horizontal Centripetal Forces**
 * Friction force causes the car to move to the center
 * **Orbital Speed**
 * Force of gravity equals centripetal force
 * **Lab**
 * Objective: What happens to the period when you increase the radius of a conical pendulum
 * Hypothesis: As the the radius gets larger, the period takes longer.
 * Reasoning: It takes more time to cover a larger area
 * Data
 * [[image:B2.JPG]]
 * [[file:Lab9.xlsx]]
 * Calculations
 * Angle of string
 * sin(theta)=o/h
 * sin(theta)=1/2.64
 * theta=sin^-1(1/2.64)
 * theta=67.74 degrees
 * Theoretical velocity
 * g/tangent(theta)=v^2/r
 * 9.8/tan(67.74)=v^2/1
 * 4.01=v^2
 * v=2 (m/s)
 * Theoretical Time
 * (2*pi*r)/v=t
 * (2*3.143*1)/2=t
 * 6.286/2=t
 * t=3.143 (s)
 * Percent error
 * abs(t e -t t )/t ﻿t *100%
 * abs(3.16-3.14)/3.14*100%
 * .02/3.14*100%
 * .005*100%
 * .5% error
 * Analysis
 * The data shows the opposite of the original hypothesis. The data shows that there is an inverse proportion between the radius a conical pendulum travels and the time it takes to complete a rotation. The error is due to the fact that there is a human reaction time to take into account. There is also a problem with where the timer was positioned, because the point where they timed for a rotation may have been at a slant. there could also be that the pendulum was not moving in a perfect circle.

__** At Home **__

>>> >>> >>>
 * **Applications of Circular Motion**
 * Which direction is friction force pointed in?
 * Friction force is pointed inwards to the center of the circle.
 * What does the free body diagram look like?
 * [[image:http://www.physicsclassroom.com/Class/circles/u6l2a3.gif]]
 * What types of circular motion on a roller coaster are there?
 * There are banked turns, hills, dips, and clothoid loops.
 * What is a clothoid loop?
 * They are loops that do not have the same radius all around.
 * They look like a tear drop.
 * What type of acceleration is on a clothoid loop?
 * There is an acceleration in both speed and direction.
 * There is also an inward acceleration due to centripetal force.
 * [[image:http://www.physicsclassroom.com/Class/circles/u6l2b3.gif]]
 * What are the center of the circles in dips and hills?
 * In dips, the down hill curve has one circle above the curve, while the up hill has either the same circle or an entirely different circle above the hill.
 * On hills, there is a single circle bellow the tracks.
 * [[image:http://www.physicsclassroom.com/Class/circles/u6l2b8.gif]]
 * How does this work in athletics?
 * By tilting the body inwards, it causes a centripetal force to cause the athlete to turn.
 * [[image:http://www.physicsclassroom.com/Class/circles/u6l2c3.gif]]

== =Day 9=

** Lesson 17 **
__**In Class**__


 * ** Definition **
 * Work
 * There must be force
 * The force exerted on object must be on the same axis as the object moves
 * The object must move
 * When force and direction are perpendicular no work is being done
 * Kinetic energy
 * Energy due to an objects moving
 * Any object that moves
 * Gravitational Potential Energy
 * Energy possessed by an object that is above or below the zero level
 * The potential energy is relative to the zero level
 * Zero level can change
 * No matter where the zero level is, the change in energy is the same
 * Elastic Potential Energy
 * Energy possessed by an object due to a compressed or stretched spring
 * ** Units/Symbols **
 * Work
 * W
 * Kinetic energy
 * KE
 * Gravitational Potential Energy
 * PE g
 * U g
 * Elastic Potential Energy
 * EPE
 * PE s
 * Units for all is Joules (J)
 * ** Equation **
 * Work
 * W=F*d*cos(thi)
 * Thi is angle between force and direction of motion
 * Kinetic energy
 * KE=(1/2)*m*v^2
 * Gravitational Potential Energy
 * GPE=(m*g)*h
 * y can substitute h
 * y and h are the vertices position
 * Elastic Potential Energy
 * EPE= (1/2)*k*x^2
 * k is a spring force constant
 * x is the distance it stressed or compressed
 * ** If it is there or not **
 * Work
 * If there is normal, tension, or friction along the axis of motion
 * Kinetic energy
 * As long as the object is moving
 * Gravitational Potential Energy
 * Object is above or bellow zero position
 * Elastic Potential Energy
 * Stretched or compressed spring
 * ** Law of conservation of energy **
 * Total amount of energy must remain the same
 * Initial Energy(+Work)=Final Energy+(Work)
 * Work can be use to put in energy or take it out
 * ** Lab **
 * Objective: What is the relationship between GPE?
 * GPE=W
 * mgh=Fd
 * d is the dent
 * Content

__**At Home**__
 * **Work, Energy, and Power**
 * How do you define work?
 * Work is a displacement caused by a force and the force must be the cause by the work.
 * Mathematically
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l1a1.gif width="196" height="18" align="bottom"]]
 * f is force
 * d is displacement
 * cosine (theta) is the angle between the force and displacement
 * Negative work is work going against the displacement.
 * Standard Unit
 * **1 Joule = 1 Newton * 1 meter**
 * What is potential energy?
 * Potential energy is the stored energy by an object due to the position.
 * What types are there and what are the definitions?
 * Gravitational Potential Energy
 * The potential energy is due to a vertical displacement, the greater the height, the greater the potential energy.
 * PEgrav = m *• g • h
 * m stands for mass
 * g stands for acceleration due to gravity
 * h stands for height above a zero point
 * Elastic Potential Energy
 * Potential energy stored in an object due to the stretch or compression of a matter[[image:http://www.physicsclassroom.com/Class/energy/u5l1b6.gif width="377" height="150" align="bottom"]]
 * What is kinetic energy?
 * Kinetic energy is the energy of motion such as vibrations.
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l1c1.gif width="206" height="55" align="bottom"]]
 * Units are joules
 * What is mechanical energy?
 * It is the energy an object acquires due to work being done.
 * It can be either potential energy or kinetic energy.
 * Any object with either potential or kinetic energy can do work.
 * What is power?
 * It is the rate of work done in an amount of time.
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l1e2.gif width="201" height="60" align="bottom"]]
 * Units are watts

[|Video]

**Lesson 18**
__**In Class**__


 * **Lab**
 * Objective: How does an air bag protect you during an accident?
 * Hypothesis: The airbag absorbs the impact of a person head whipping forward increasing the amount of distance of impact and decreasing the force.
 * Reasoning: There is more in-front of the body to disperse the force of the body hitting an object.
 * Materials:
 * 2 eggs
 * bowl filled with flour
 * meter stick
 * 2 zip-lock bag
 * stopwatch
 * [[image:tclarke2o12:Snapshot_20110708.JPG width="254" height="230" caption="Snapshot_20110708.JPG"]]
 * Set up
 * [[image:sophies-physics:setup.JPG caption="setup.JPG"]]
 * Chart [[image:F4.PNG]]
 * [[file:Air Bag Lab.xlsx]]
 * Equations
 * What is the initial gravitational potential energy?
 * GPE=m*g*h
 * GPE=(.05213)(9.8)(.25)
 * GPE= 0.128 (J)
 * How much work is done in each trial?
 * W+GPE=0
 * W+(m*g*h)=0
 * W+(.05213*9.8*.25)=0
 * W+.1277=0
 * W=-0.128 (J)
 * How much force was used to stop the egg in each case?
 * W+GPE=0
 * (f*d)+(m*g*h)=0
 * (f*-.001)+(.0213*9.8*.25)=0
 * (f*-.001)+.1277=0
 * f*-.001=.1277
 * f=127.7 (N)
 * Questions
 * 1) In a crash the egg would represent the person's head, the table would represent the windshield, and the flour would represent the air bag.
 * 2) Gravitational Potential Energy is the amount of energy stored in an object due to it being not at the zero level. Kinetic energy is the energy an object possesses due to motion. Work is how much energy is being added or taken out of a system.
 * 3) An objects kinetic energy is determined by it's velocity and mass.
 * 4) Work either adds energy in or takes it out of a system.
 * 5) The greater the distance the less force there is for the same amount of work.
 * 6) A softer collision cause there to be a greater impact distance lessening the force.
 * 7) The cushion increases the amount of time for the impact and the distance a force is dispersed over.
 * 8) Since the total energy of system can only be taken out by work and the amount of force felt by the passenger needs to be minimal, the conservation of energy provides a way to remove energy.
 * Conclusion
 * Air bags create a greater distance lessening the force acted on a person during a crash, do they use the equation W=f*d to reduce the energy. As seen in the lab the distance of impact increased as the kinetic energy increased allowing less force to act on the egg.
 * Measurements are major points of error. the length of the egg is hard to calculate since it is not straight and the depth the egg went in could be off since the ruler may have sank into the flowerand again the egg is not easy to measure.
 * By creating a delivery system to ensure the egg fell in the same spot and the same way, with increments to know how high we are dropping it from and how much it sinks.
 * Measurements are major points of error. the length of the egg is hard to calculate since it is not straight and the depth the egg went in could be off since the ruler may have sank into the flowerand again the egg is not easy to measure.
 * By creating a delivery system to ensure the egg fell in the same spot and the same way, with increments to know how high we are dropping it from and how much it sinks.

__** At Home **__ >>>
 * ** The Work-Energy Theorem **
 * What are internal forces and what are external forces?
 * External forces can change total mechanical energy, internal can't.
 * Total force is always conserved.
 * **Internal Forces**
 * **Fgrav**
 * **Fspring**
 * **External Forces**
 * **Fapp**
 * **Ffrict**
 * **Fair**
 * **Ftens**
 * **Fnorm**
 * How does work connect to situations externally? Where energy is conserved?
 * Externally
 * The following equation is used to ensure that there is no loss in energy.
 * **KEi + PEi + Wext = KEf + PEf****﻿**
 * W allows energy to be taken out or added in to a system of forces.
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l2b5.gif width="248" height="266" align="bottom"]]
 * There is no work when energy in a system is conserved.
 * So one force increase while another decreases.
 * Like on roller-coasters:
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l2b22.gif width="434" height="155" align="bottom"]]
 * How can you represent the thereon in a chart?
 * For a shift from one type of energy to another:
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l2c4.gif width="261" height="132" align="center"]]
 * For work having been done:
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l2c6.gif width="256" height="154" align="center"]]
 * To show total energy in a point:
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l2c16.gif width="458" height="193" align="bottom"]]