Wednesday 12, 2008

On Wednesday we actually didn't do much.Mrs.K gave a review on circular motion and work and energy. Which took half of the class, afterwords Mrs.k gave us a brief article about space.Also we were given this assignment where you have to write about a historical technology or a particular planet, indicating whether its inhabitable or not, and such. The assignment is due on Nov 27, and a presentation is required.

Nov. 10

Today in physics we had a Remembrance day assembly, yeah.
Well, we also had physics class.
Today in physics we had a substitute teacher, named Mrs. Karras, she's pretty cool.
Anyways, we didn't do much at all in physics class, we just corrected the questions we got over the weekend. They were p.213-214 questions: 1-5, 9-12, 17-20 and p.237-238 questions: 1-4,12-14, 20-21.
The next scribe will be Yonas, cause he said we were absent.. and we fell for it. Life sucks.

Energy Transfer & Hooke's law

For today's class, we were given some time to work on the worksheet called "Energy Transfer" and and we also went over them. And for anyone who didnt get the answers here they are.

1. Potential Energy and Kenetic Energy are the two types of energy that occurs in the spring- block system.


2. PE is the energy position and KE is the energy due to motion.


3. The kinetic energy is at a maximum when the distance = 0 , because thats when speed is the greatest.


4. The potential energy is at a maximum when the speed = 0.


5. As the potential energy increases the kinetic energy decreases. And this is an example of a closed system.


6. The sum of the KE and PE stays constant. This demonstrate the Law of Conservation of Energy.


7. The PE and KE equal to 4 times during one cycle.


8. No, this cycle will not repeat forever because the displacement decreases.


9. If the cycle stops the energy goes to the board.


10. If the spring were vertical gravity would've affected the box which would result in an open system.

After going over the answers, we were given the rest of the time to work on our Lab from the class before. And we were also given question to do from the green book pages 213-214 questions number 1-5, 9-12, 17-20 ; pages 237-238 questions number 1-4, 12-14, and 20-21. the questions are DUE ON MONDAY.

AND DONT FORGET THAT THERE WILL BE A TEST ON THURSDAY, SO DONT FORGET TO STUDY !

And the next scribe is FRANCIS.

Ugly Weather, Winter's Coming... Let's Scribe!

Hello :)

So today's class was very straight forward, we were given a lab to do related to Hooke's Law. We had to find the relationship between the extension in an elastic spring and the applied force. The materials that were needed for the apparatus were a stand, ring clamp, elastic metal spring, and a meter stick. We had to attach the spring to the ring clamp and adjust the spring so the lower end is on the zero point of the meter stick, or at a constant spot during the observations. Then we had to make a chart similar to the one on the paper like so:



Then we had to hang mass on the spring, and record the extension of the spring. We had to repeat the previous step for each of the mass given. Then we had to plot the graph (question 6 on the paper) and answer questions 7-11.

Don't forget to answer the Practice questions 1-5 shown on the back of the lab paper. The answers are given just show your work and how you got those answers.

Make sure to hand in yesterday Wind-up Toy Lab that was due today.
Today's lab 10.1: Hooke's Law is due TOMORROW!

No school Tuesday (Remembrance Day) ,
TEST on Wednesday so.. STUDY PEOPLE!

That's all for today's class,
your next scribe is christine d.

Bye :)

Scribe Time

Hi this is benofschool, and I'll be your scribe for today...

We started off correcting chapter 11.2 Study Guide. So here are the answers:

enter, leave, external, conservation of energy, form, constant, created, destroyed, mechanical, decrease, simple harmonic, potential, kinetic, potential, kinetic, increases , decreases , friction , thermal

Here are the answers for the second paragraph:
shape, potential, kinetic, all, conserved, some, other forms, conserved

Now we corrected a couple of worksheets from the beginning of the week.
Here are the answers for Concept- Development Practice Page: Chapter 8: Energy

1)
W= Fd
W= 200N (4m)
W= 800J

2)
P = W/t
P = [200N(4m)]/4s
P = 200 watts

3)
P=W/t
P= 6000 watts or 6kw

4) 16nore (IGNORE :P)

5) 10 m/s of all of the cases. Apply trajectory formula to answer this question.

6) Block A wil reach the bottom of the incline first because of the incline's shorter distance.

7) 100J, 75J, 25J

8) 10 m/s for Points B, D, and E. Max Speed at Point C

9) Yes there will be a change in wind speed because the windmills will take some of the wind's kinetic energy.

That was it for that work sheet. There was one more. Diagram Skills Section 5-3.

1a) 0 J

b) E_p = mgh

c) E_k = (1/2)mv²

d) E = mgh_A - mgh_B

2a) 0 m/s

b)v= sqrt(2E_k/m)

3) First Column: All 0
Second Column: All 19110J
Third Column: 9555J, 12740J, 15925J, 3185J, 6370J
Fourth Column: 9555J, 6370J, 3185J, 15925J, 12740J
Fifth Column: 17m/s, 19.8m/s, 22.1m/s, 9.9m/s, 14m/s

4)The values are equal.

After that we took a look at our Work and Energy Booklet and learned about spring energy and the potential energy of the spring otherwise known as HOOKE'S LAW.

The formula for Hooke's Law is F = kx where F is the force, k is the spring constant, and x is displacement of the spring if it is stretched using the spring at normal length as the reference point. So now we can calculate the potential energy of the spring we are given a new formula derived from Hooke's Law and our good old area of a triangle of a Force vs Displacement graph.

W = area of a triangle
W = (1/2) F x
W = (1/2) k x x ---Now we substitute F for Hooke's Law
W = (1/2) kx²

Now we have 2 Potential energy formulae:

E_p = mgh
W = (1/2)kx²

We started working on a lab that involved Wind Up toys. This lab is due tomorrow I believe. Other than that just study up because the test on Circular Motion and Work and Energy will be on Wednesday November 12, 2008. The next scribe will be my best friend Rojuane...

Bye Bye

October 31, 2008

This Halloween in physics we did a Lab using a ramp, a cart, and a meter of floor, to measure potential energy and kinetic energy. With this lab we received a lab sheet which is due on Monday, We also received a chapter study guide which will be corrected in class.

The next to scribe is Benchmen.

Work and Energy Study Guide

Previous scribe was abducted by aliens and hasn't scribed ever since, so I inherited his scribing powers under the "first come, first serve" rule.

The study guide is straightforward. Basic stuff. Grade 12 physics students can do this in their sleep.


10.1 WORK AND ENERGY STUDY GUIDE

Note: Capitalized words are the answers to fill-in-the-blanks.

Work
Work is the product of the FORCE exerted on an object and the DISTANCE the object moves in the DIRECTION of the force. The equation used to calculate work is W = Fd. In this equation, W stands for WORK, F stands for FORCE, and d stands for DISTANCE. Work has no direction, so it is a scalar quantity. The SI unit of work is the JOULE. When a force of one NEWTON moves an object a distance of one METRE, one JOULE of work is done. Work is done on an object only if the object MOVES. Work is done only if the FORCE and the DISTANCE are in the same direction.

Work and Direction of Force
If a force is exerted IN THE DIRECTION OF the motion, work is done. If a force is exerted PERPENDICULAR to the motion, no work is done. If a force is exerted at another angle to the motion, only the component of the force IN THE DIRECTION OF the motion does work. The magnitude of this component is found by multiplying the force applied by the COSINE of the angle between the force and the DIRECTION OF THE MOTION. When friction opposes motion, the work done by friction is NEGATIVE. When work is done on an object, ENERGY is transferred. Work is the transfer of energy as the result of MOTION. This transfer can be POSITIVE or NEGATIVE.

Power
Power is the RATE of doing work, or the RATE at which ENERGY is transferred. The equation used to calculate power is P = W/t. In this equation, P stands for POWER, W stands for WORK, and t stands for TIME. The unit of power is the WATT. One JOULE of energy transferred in one second equals one watt. This is a very small unit, so power is often measured in KILOWATTS.

1. Symbol for kinetic energy: K
2. Calculation of kinetic energy: mv^2/2
3. Symbol for work: W
4. Calculation of work: Fd
5. Statement that the work done on an object is equal to the object’s change in kinetic energy: Delta K = W
6. Equivalent to 1 kg*m^2/s^2: 1 J

7. Through the process of doing work, energy can move between the environment and the system as the result of FORCES.
8. If the environment does work on the system, the quantity of work is POSITIVE.
9. If the environment does work on the system, the energy of the system INCREASES.
10. If the system does work on the environment, the energy of the system DECREASES.
11. In the equation W = Fd, Fd holds only for CONSTANT forces exerted in the direction of displacement.
12. In the equation W = Fd cos theta, angle theta is the angle between F and the X-AXIS.


13. W > 0: B, E, F
14. W = 0: A, D
15. W < 0: C


16. What was the magnitude of the force acting on the crate? 30.0 N
17. How far did the crate move horizontally? 0.50 m
18. What does the area under the curve of this graph represent? work
19. How much work was done in moving the crate 0.1 m? 3.0 J

20. Rate of doing work: power
21. Unit of power: watt
22. Symbol for power: P
23. Calculation of power: W/t
24. 1000 watts: kW

Next scribe is KAMIL.

October 29, 2008: Work and Power

In today's class we finished the rest of the question in Concept-Development Practice Page 9.2.
The answer to them are:
4.
a) normal
b) normal

5.
a)Yes
b)Provides centripetal force for circular motion.

After that, Mrs. K handed back our lab and assignment (questions 4 and 5), with it she gave us a small booklet on our last unit in mechanics, Work and Energy, which contains a small introduction to Calculus. We only read the first 4 pages then right after we started a new lab relating to the equations mentioned in the booklet.

Page 1
Page 2
Page 3
Page 4

At the end of the class we were given a chapter 10 study guide.

Finally the next scribe is Vieteran!!