Accuracy and Precision

Accuracy and precision: In the fields of science, engineering, industry and statistics, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to its actual value.

The precision of a measurement system, also called reproducibility or repeatability, is the degree to which repeated measurements under unchanged conditions show the same results. Although the two words can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method.

A measurement system can be accurate but not precise, precise but not accurate, neither, or both. For example, if an experiment contains a systematic error, then increasing the sample size generally increases precision but does not improve accuracy. Eliminating the systematic error improves accuracy but does not change precision.

Accuracy versus precision; the target analogy

The analogy used here to explain the difference between accuracy and precision is the target comparison. In this analogy, repeated measurements are compared to arrows that are shot at a target. Accuracy describes the closeness of arrows to the bullseye at the target center. Arrows that strike closer to the bullseye are considered more accurate. The closer a system's measurements to the accepted value, the more accurate the system is considered to be.

High accuracy, but low precision

High precision, but low accuracy

To continue the analogy, if a large number of arrows are shot, precision would be the size of the arrow cluster. (When only one arrow is shot, precision is the size of the cluster one would expect if this were repeated many times under the same conditions.) When all arrows are grouped tightly together, the cluster is considered precise since they all struck close to the same spot, even if not necessarily near the bullseye. The measurements are precise, though not necessarily accurate.
However, it is not possible to reliably achieve accuracy in individual measurements without precision—if the arrows are not grouped close to one another, they cannot all be close to the bullseye. (Their average position might be an accurate estimation of the bullseye, but the individual arrows are inaccurate.) See also circular error probable for application of precision to the science of ballistics

yesterday we did a lab on "Experiment- petermination of the earth's gravitation field strength ."
so if you didn't do it, ask mr.vicent for help :)

Dynamics Review Answers

Here are the answers for the Dynamics Review:

Dynamics review answers

Have a good weekend.

Mr. V

Dynamics Test Review

We went over the Dynamics Test Review in class today and Mr. Vincent will be posting the answers to the review sometime on Sunday. For fun, I will answer some random review questions and show you how to get the answer.

Practice Problems

5. A grapefruit of mass 0.5 kg is accelerated at 10 m/s². How large is the force acting on it?

Given:

(m) Mass = 0.5 kg

(a) Acceleration = 10 m/s²

(F) =?

F = ma

F = (0.5 kg) (10 m/2²)

F = 5 kg•m/s²

F = +5 N

8. A box is pushed across the floor with a force of 120 N, but experiences a frictional force of 55 N. If the acceleration that results is 1.1 m/s², what is the mass of the box?

Since friction is a resistance to force, the 55 N is subtracted from the applied force to give us the net force.

F_net = F_Applied + F_Friction

F_net = 120N + (-55N)

F_net = 65 N

We now have force, are given acceleration (1.1 m /s²), and can solve the equation for mass.

F = ma

m = F / a

m = 65 N / 1.1 m/s²

m = 59 kg (2 significant digits)

Conceptual Review

7. A 600-kg car and an 1800-kg truck go from zero to 100 km/h in 10 seconds flat. Calculate the acceleration of each vehicle, including units with your answer. Do they have the same acceleration? Is the same force required to cause this amount of acceleration in each vehicle? Explain using Newton's laws of motion.

First thing to do is convert 100 km/h to meters per second. This is done by dividing by 3.6.

100 km/h

------------ = +27.8 m/s

3.6

Both vehicles reach this speed in 10 seconds, so their acceleration must be the same:

+27.8 m/s ÷ 10s = 2.78 m/s²

Now that we have both vehicles accelerations (2.78 m/s²) and masses, we can solve for the force both vehicles are exerting.

Do they have the same acceleration? Yes, 2.78 m/s

Is the same force required to cause this amount of acceleration in each vehicle? Explain using Newton's laws of motion.

The truck requires more force to accelerate at that rate because it has more mass.

The explanation would come from solving the force for each vehicle using Newton's 2nd law, Force = mass x acceleration:

Truck (1800-kg):

F = ma

F = (1800 kg) (2.78 m/s²)

F = 5004 N

Car (600-kg):

F = ma

F = (600 kg) (2.78 m/s²)

F = 1668 N

The truck needs almost 3x more force than the car to move at 2.78 m/s².

December 7th/2010

we have a hand out called "Free-body Diagrams," in this booklet we are learning about free body diagrams (duh!!) ;D, anyways we did the first 8 examples in class and the rest we are suppost to do on our own. it's only 4 questions and it's towards the end of the booklet. also i'm pretty sure the teacher will do a homework check tomarrow (i think).

Kinematics Review - Answers

Here are the answers for the Kinematics review. Best of luck on the test. **PS: the test will not include the final two formulas provided on friday. Only the formula for average velocity and average acceleration will be needed. These will be provided on your formula sheet.
Mr. VKinematics review answers

Acceleration review answers

Here are the answers for the acceleration review:

page 1

1. +6.3 m/s²

3. +35.5 m/s

5. +107 m/s

page 2

1. 15 m/s and 18.8 m

3. 1 .5 m/s² and 116 m

5. 250 m

page 3

1. 2.94 m/s and .44 m

3. 25 m/s

5. 76.7 m/s

Review package answers will be up right away. Good luck.

Mr V.

November 26/2010

Guys we have a test on tuesday and Mr. Vincent also gived us a preview (only problem is it doesn't have the answer) BUT DO NOT WORRY...he'll post the answers on sunday night and if you still have quesitons than go ask him on monday 'cause you'll still have a day before the test :) good luck!!!! have a wonderful day ;) love you all!!!!!!!

novermber 23

we continued on doing graphs but today we did a different graph ( yes people not all graphs are the same.....hahahaha...well don't worry i'm not getting this lesson either) anyways so today we did v-t graphs. and you need to review your notes in order to get these. Actually go to the teacher for the sake of arugment :) . and that's your update for november the 23

Position-time graphs

Here are the class notes from today.Cheers,Mr Vposition-time graphs

Class notes from friday

Class notes from Friday. Hope everyone had a good weekend.Mr. V Intro to d t graphs

Class notes, Thursday, Nov 18th

Vector island part 2 and quiz review

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Sorry about the delay. Left the flash drive at school yesterday. Here are the notes from yesterday's class.

Mr. V.

Class notes, Wednesday 17th

Here are the notes for Wednesday, Nov 17th, a reminder that maps (fully completed and very colorful) will be due on Monday. Please read the instructions carefully and make sure that all required parts are included.
Mr. V
Class notes, Wednesday, Nov 17th

November 17, 2010

At the beginning of the class, Mr. Vincent gave us a quick review about how to calculate Velocity and distance. He also provided some formulae and examples that could be useful in some ways. Vector requires magnitude and direction while Scalar doesn't. An example of a scalar is speed and an example of a vector is displacement. After that, we did an activity called "Creating a pirate treasure map" where we are asked to make and design our own pirate treasure map using vectors. We didn't able to finish it today so we will continue it tomorrow.

Tuesday, Nov 16th --> class notes

Class notes, tuesday nov 16thHope everyone is adjusting well to having a new teacher in class. Looking forward to spending the next 6 weeks with all of you. Here are the notes from Tuesday's class if you missed anything.
Mr. V

November 12/2010

we did our unit test, hope you all did good WITHOUT CHEATING!! anyway our next unit will be kinametics (hope i spelled that right, and if not ......well screw you physics) which will be taught by our student teacher Mr. Vencelin or Vinclin or Victorm or .......gee i'm not so sure.........but yeah by that teacher. For this unit the best i can say is that you should all be reviewing grade 10 notes on physics cause this unit will contain all of that d=vt or stuff like that....SHUT UP DON'T ASK ME JUST GO OVER YOUR GRADE 10 UNIT ON PHYSICS. well hahahhahah..... anyways i hope we will all be getting along towards our new teacher without having crush on him (that goes espically for mr. leparone). AND THAT'S YOUR UPDATE FOR FIRDAY NOVEMBER THE 12!!!

November 10, 2010

Today, we went over "Young's Experiment Problems" worksheet.

We used the equation:

Wavelength = xd/L

We also talked about The Photoelectric Effect and the Wave-Particle Duality. According to the book, photoelectric effect is the emitting of electrons when electromagnetic radiation falls on an object. It can be studied through a photocell. Electrons are ejected only if the frequency if the radiation is above a certain minimum of value called the threshold frequency (fo). Albert Einstein studied and explained the photoelectric effect and he describes it as discrete bundles of energy called photons.

November 5, 2010
Today, we went over the answers for the pink sheet, "Appendix 2.4: Chart for Evaluating the Models of Light" and all the answers from 1-12 in the green booklet, "The Nature of Light: Part 2. The Wave and Particle Models of Light Problems". The answers will be posted by Mrs. K on blogspot.

November 5, 2010

At the beginning of the class, we went over the answers in NOL2 problems #'s 1-12. Mrs. K posted the answers in this blog by the way so if you don't get a chance to copy them, be sure you do! We then watched couple of videos related to Wave Theory.

A new formula was introduced to us and said to be useful:

wavelength = (x)d/L

wherein:
x is the distance between adjacent nodal lines on a screen.
d is the separation between the slits.
L is the perpendicular distance from the slits to the screen.

A worksheet was given to us related to this formula for practice. Be sure to answer it.

NOL 2 Problems

Nol2 problems

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Nov. 4 '10 - Wave Theory of Light

Today we went over the Wave Theory of Light. Just like what we did for the Particle Theory, we were to complete a worksheet called Appendix 2.4: Chart for Evaluating the Models of Light; Model: Wave Theory (pink sheet this time :D). It did come to my attention that the theory did not provide explanations for dispersion and the speed of light. Is it just me or is that the case?

Further in the questions book we are supposed to answer 9-12 for homework. We will be going over all questions (1-12) tomorrow!

Wednesday, Nov. 3

Yesterday we went over page 8 to 11, we talked about Determining the Speed of Light.
Ms. K gave us time to work on the the assignment she gave us on Monday "Contributions to the Determination of the Speed of Light", it's due today. She also gave us " The Nature of Light: Part 2
The Wave and particle Models of Light Problems" we are suppose to finish the question for today, but if you didn't we are going to go over it today in class.

November 3, 2010

Today we went over pages 8 to 11 in our NOL2 booklet, and highlighted key points about each person's experiments, observations, and conclusions. Afterward we were given time to complete our worksheet from Monday called "Contribution to the Determination of the Speed of Light". We had access to the internet to search some interesting points about our chosen person's life. If you were not able to complete it today, you still have tomorrow to hand it in.

For homework, we are to do questions 1 to 8 in the NOL2 questions booklet. We will go over the answers tomorrow in class :)

Newton's Corpuscular Theory and Reflection

yesterday's class was pretty much about Newton's Corpuscular Theory, but first thing we had to hand in the four theories( tactile, emission, wave, particles), in which we had to describe who when and what do the theories explain, and draw a diagram for each illustrating how they work.

Then Ms K explained about the Newton's Corpuscular Theory, the theory explains that light has small particles called corpuscles which travel in straight line, good evidence that light travel in straight line is a shadow of a building in sunny day, you will notice a nice smooth straight line along the sides of the wall.

Later we worked on a yellow sheet "Chart for Evaluating the Models of Light" then ms K went over it on the class. Last but not least we were given a homework due Wednesday "Contributions to the Determination of the Speed of Light" in which you have to pick a scientist and fill the boxes

November 1, 2010

I hope everyone had a good halloween and lots of candies without cutting in front of little kids!

So today the first worksheet (from Friday) for The Nature of Light: Part II (The Wave and Particle Models of Light) was due - which required us to summarize the Tactile, Emission, Particle/Corpuscular, and Wave Theory of light as well as to make a diagram for each of them. If you did not get the chance to hand it in, do so as soon as possible. Term 1 ends this Friday, November 5!

Today's lesson went more into detail of Newton's Particle (Corpuscular) Theory of Light. We worked on a sheet titled Appendix 2.4: Chart for Evaluating the Models of Light; Model: Particle Theory. It is a yellow sheet in case you missed the class. You need it to know what the theory states, and also to know what is true about the characteristics of light particles! (I think..)

For homework to be handed in on Wednesday (half day tomorrow, yay!), please be sure to complete the worksheet called "Contribution to the Determination of the Speed of Light". You are to pick one person, and fill in each box on the sheet with the information needed. You can find what you need in the NOL Part 2 booklet, pages 8 to 11. Goodluck!

october 27/10

we got our test back and we did had to do the tactile, emission, particle and wave theory/draw to in one of the pages miss. K handed out. Plus we got another work sheet called unit conversions: and the answer for those are
1) 6000m
2)4900g
3)75mm
4)3210cg
5)56m
6)0.76kg
7)4500000m2
8)1.23kg/L
9)1.2x10 to the po

October 29, 2010

At the beginning of the class, we went over our tests about Nature of Light Part 1. Mrs. K gave us each and every detail from it. Then, Mrs. K introduced a new lesson entitled Nature Of Light Part 2: The Wave and Particle Models of Light. We then highlighted some important details in the first topic and learned 4 theories that are developed ages ago.

We were given two handouts:
Unit Conversion (for conversion practice.)
A worksheet that you are asked to explain how each theories (Tactile, Emission, Particle, Wave) describes light. You are also asked to draw a picture at the back of it. (It needs to be handed in on Monday! Be sure to do it!)

October 27th, 2010

Today in class, we went over the answers for worksheets:

• Transparency 1-1
• Transparency 1-2
• Transparency 1-4

Ms. K uploaded the answers to Slideshare, and can be found in the previous post or here.

We were also given the optional worksheet titled
Reinforcement: Determining Relationships from Graphs,
which was more graphing practice.

There's a test tomorrow on this unit; make sure you know the basic elements of a graph (giving names for the axis and having the units for them in brackets, going up by appropriate units on the graph, an appropriate title that describes the graph, knowing what kind of relationship the graph is showing, etc). Good luck

Nature of Light Part 1

Nature of light part 1

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October 18, 2010

Today we did a lab where we had a "mystery box" that we had to shake and write an "observation", a "conclusion", find a "pattern" and draw a diagram for. For example, your observation can be the different types of sounds you hear while shaking the box, like the sound of a bell or sounds of metal tapping against each other. Your conclusion is what you think is in the box, and the pattern will be the continuation of a sound you hear while shaking the box a certain way. After doing the observation, conclusion, and finding a pattern, we were to open the box and draw down the diagram of what we thought was in the box, and what was really in the box. After we were done, we had to hand in our lab in order to get our test returned to us.

October 14th

In today's class, we did three questions from our booklet which was questions 21(a,b,c) 22 and 26.
We also went over on what to review on the upcoming test. The review included pages from the booklet or the "summary" near the end if a condensed version of the whole thing is wanted instead(not including the page 14 sound perception/sound wave characteristics guide.

October 13, 2010

We made a straw oboe by trimming the end of a drinking straw and placed the flattened double reed part of the straw oboe between our lips to play it. We learned that the reed vibrates to make sounds. We also did some problems from the sound unit booklet.

Concept-Development Practice Page 26-1

Concept-Development Practice Page 26-1

Sound:

1) Two major classes of waves are longitudinal and transverse. Sound waves are:

Answer: Longitudinal

2) The frequency of a sound signal refers to how frequently the vibrations occur. A high-frequency sound is heard at a high:

Answer: Pitch

3) The sketch questions answer would be: 2.5

4) Compared to the wavelengths of high-pitched sounds, the wavelengths of low-pitched sounds are:

Answer: Long

5) Suppose you set your watch by the sound of the noon whistle from a factory 3 km away:

a. Compared to the correct time, your watch will be:

Answer: behind

b. It will differ from the correct time by:

Answer: 9 seconds

6) Sound waves travel fastest in:

Answer: solids

7) If the child’s natural frequency of swinging is once each 4 seconds, for maximum amplitude the man should push at a rate of once each:

Answer: 4 seconds

8) If the man is Question 7 pushes in the same direction twice as often, his pushes:

Answer: will not

Be effective because

Every other push will oppose the motion of the swing

9) The frequency of the tuning fort is 440 hertz. It will NOT be forced into vibration by a sound of:

Answer: 220 hertz

10) Beats are the result of the alternate cancellation and reinforcement of two sound waves of:

Answer: slightly different frequencies

11) Two notes with frequencies of 66 and 70 Hz are wounded together. The resulting beat frequency is:

Answer: 4 hertz

12) The accepted value for the speed of sound in air is 332m/s at 0⁰C. The speed of sound in air increases 0.6m/s for each Celsius degree above zero. Compute the speed of sound at temperature of room you are now in:

Answer: 332m/s+ (0.6) (20⁰C)

=344m/s @20⁰C

Sound Unit

Today we began to study "Sound" for our next lesson. To start this lesson off we did a lab. Using a ruler, tuning fork, cylinder and water, we learned how to create sounds with them and how to vary their pitch. The material covered was somewhat new to me and from what we learned so far I don't think it's a hard concept to understand.

october 1/2010

today we had our UNIT test :)
hope you all did good ;)

Waves in Two Dimensions Review

Waves2 Dreview

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Scribe List

This is The Scribe List. Every possible scribe in our class is listed here. This list will be updated every day. If you see someone's name crossed off on this list then you CANNOT choose them as the scribe for the next class.

tbooda breezy afroman3540(2) George ninja800 AiswaryaRai(3)

CtC Patrick supersauce Cedric! Robby(2)

tippsy123(2) John F ngerner(3) Ace OranjeZ zazu

This post can be quickly accessed from the [Links] list over there on the right hand sidebar. Check here before you choose a scribe for tomorrow's class when it is your turn to do so.