Forces

=__Forces__= PLEASE POST DAILY NOTES HERE. ORGANIZE THEM AS FOLLOWS:

Unit: Topic: Text Reference: Idea: Definition: Key Examples: Additional Information/Interesting Links/etc.

 * You may want to add stuff to others' notes so we can all have full notes for exam, but do inform the original posting student please.

**Wednesday, March 23, 2011** **Arlanna Pugh** **Unit: 3** **Topic:** Forces Brainstorm **Text Reference:** Unit B: Energy and Momentum Introduction (pg. 185) **Idea:** Groups rotated to different tables starting and adding to many brainstorms on concepts relating to Forces and Movement. Ideas were recorded on chart paper. All chart papers were filled, proving that we all have an sufficient amount of knowledge relating to forces! **Definition:** N/A *Beginning of class spent watching Imax Film: Tornado Alley.

** March 30, 2011 ** **Unit 3**: **Topic**: Introduction toForces **Text Reference**: Section 1.14- Friction and the Normal Force (44-48)
 * Marco Becerril **

µ= Properties of surface FN= Normal Force Ffr= Force of Friction

__** Forces **__ ΣF= F1+F2

Can be solved by using two different methods: Fnet=0 __ Fg __ = __FT2__ = __FT1__ sin a......sin b.....sin c
 * __ Static Situations (No friction) __**
 * 1) Vector Addition **

Fnet=0
 * 2) **
 * [[image:http://upload.wikimedia.org/math/d/2/1/d21e3d53f78769beee8ff7b6c4a9a92c.png caption="perp"]]balanced forces **

ΣF =0

0=FT1 +FT2 -Fg

__** balanced **__ ΣF=0

0= FT2 //-FT1// //* Worked on sample problems (no friction)//

** March 31, 2011 ** **Unit 3**: **Topic**: Introduction toForces **Text Reference**: Section 1.14- Friction and the Normal Force (44-48) Ffr= µFN
 * Marco Becerril **
 * __ Friction __**

**Static Friction**- object not moving. ......................-force can increase to some max. ......................-beyond max==> object moves.

**Kinetic Frictions**- object sliding on surface. ..........................- always less than static

Therefore: Ffrk < Ffrs µk ≤ Ms Ffr= µFN


 * Worked with problems (friction)

=** Ajmeet Dhillon **= =** Friday, April 1, 2011 **= =** Unit 3: **= // Text Reference: Section 1.10 - Free body Diagrams (Pg - 33 - 39) // // Section 1.14 - Friction and Normal force (Pg 44 - 48) //
 * Topic: **// ﻿Friction and Solving free body diagrams for forces and acceleration. //

//Theory -// FRICTION FF = µFN FF = Force of Friction FN = Force of Normal = force exerted by the surface. It is perpendicular to the surface. µ = Coefficient of friction. How rough or smooth the surface is. Static friction – Object not moving Kinetic Friction – Object if moving. The key idea is breaking the forces into parallel and perpendicular forces. Then we add the components and look for the required forces or acceleration. Practice - Please refer to the examples done in class and do the questions in the textbook. The questions can be found in the sections reffered above. Homework - Work on the handout named PRACTICE WITH HANDOUTS given in class.

**Tuesday, April 5, 2011** **Arlanna Pugh** **Unit: 2** **Topic:** Forces Challenge! **Text Reference:** Section 2.6 String-and-Pulley Problems (pg. 93) **Idea:** What is the optimal angle of the whiteboard to just move the weight slightly down the incline? Forces Groups had to use formulas and logic to determine the most optimal angle/solution to the challenge. Most groups arrived at an angle of approximately 20°. **Definition:** N/A **Homework:** Finish up previous forces sheets Solution to Challenging Multi-Pulley question (Answers taken up in class): Sheet Title: **Newton's 3rd Law Sample Questions** Answers: Acceleration: 3.2 m/s Tension #1: 132 N Tension #2: 183 N  Tension #3: 136 N  *Full solution to be uploaded soon!

**Wednesday, April 6, 2011** **Ali Sharif** **Unit: 2** **Topics:** Vectors and Projectile Motion - Re test **Homework:** Finish the Newton's Second and Third Law Problem Set Pg 1: #1, 4 Pg 2: #1, 3 - Due Monday

Interesting video about Newton's Laws:
media type="youtube" key="NWE_aGqfUDs" height="390" width="480" Download: #|FLV#|MP4#|3GP

**Monday, April 11, 2011** **Jennifer Taylor** **Unit: 2** **Topic:** Circular Motion **Text Reference:** pg 99 - 114 **Idea:** Groups completed "Going in Circles" package as well as took notes as follows:

T/f=Period/frequency= stays the same V=speed *speed is directed tangential to the circle (if let go mass will follow the direction of and will eventually fall due to gravity) //V//= velocity = changes |a|= magnitude of acceleration = stays the same |Fnet| =same

*examples uploaded soon

**Definitions/ Important Equations:**


 * Centripetal acceleration: ** acceleration toward the centre of the circle
 * Centripetal force: ** the sum of the forces acting toward the centre of the circle (+)
 * ** ac ** || ** Fc=mac ** ||
 * = 4π2rf2 || = m4π2rf2 ||
 * = 4π2r/T2 || = m4π2r/T2 ||
 * = v2/r || = mv2/r ||

** Tuesday, April 12, 2011 ** ** Talha Sadiq ** ** Unit: 3 ** ** Topic: ** Forces- Circular motion ** Text Reference: ** ** Idea: ** Example problems. ** Definition: ** N/A


 * 1. ****The moon’s nearly circular orbit about the Earth has a radius of 385000 km and a period of 273 days. a) Determine the acceleration of the moon towards earth.**
 * b) How fast is the moon travelling in its orbit?**
 * 2. ****A stone of a mass 0.50kg attached to a string 25 cm long is moving in a horizontal circle on a surface where friction is negligible. Determine the tension on the string. It is moving at 10 m/s.**


 * 3. ****Stone on an end of string moving in vertical circle. Determine the tension on the string at a) the top and b) the bottom of the loop. m = 500g, r = 25cm and v = 10 m/s.**[[image:Scan_1.jpeg width="720" height="981"]][[image:Scan_3.jpg width="720" height="910"]]

AJMEET DHILLON 15 April 2011 Notes - Universallaw of gravitation **__UNIVERSAL LAW OF GRAVITATION __** FG is directly proportional to mass 1 or mass 2 FG is inversely proportional to (distance between 2 objects)2

G – Universal gravitational constant = 6.67 * 10-11 Nm2 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">Kg

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">r – distance from centre of 1 body to centre of another body. <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">m1- mass of abject 1 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">m2 – mass of object 2

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">m1(yusuf) – 65kg. <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">g- 10 m/s2 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">Fg1 = mg = 65(10) = 650N

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">M2(rose) = 50 kg <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">g = 10 m/s2 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">Fg2 = 50(10) <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">= 500N

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">Fgravity = Gm1m2 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">r2 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">= 6.67 * 10-11 * (50) (65) <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">32 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0cm 0cm 0pt;">= 2.4 * 10-8N Home work - Work on universal gravitation worksheet given in class.


 * Ali Sharif **
 * Unit: 2 **
 * Topic**: Universal Gravitation
 * Text Reference:** 1.15: pages 48 - 51
 * Idea**: Newton’s Law of Universal Gravitation:
 * Definition**: Gravity is the mutual force of attraction between any two objects that contain matter, regardless of their size.
 * Key Examples:** Gravity applies to any object in space:



=Interesting Information= media type="youtube" key="Y50HeIUS4tk" height="390" width="480" Download: #|FLV#|MP4#|3GP

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