Monday, September 13, 2010

Monday, September 13, 2010

First we began our class with handing in the assignment from Friday, titled "Grade 12 Physics: Acceleration Assignment" (which if you haven't, reminder that you should!) and copied and checked answers 8 - 11 on the practice worksheet titled "Grade 12 Physics: Acceleration II."

The answers are as followed :
(Note: Thanks Amy, and I hope you like the colours added.)

8b. = 121m
8c. = 391m
8d. = 946m
9. = 15m
10. = 1350m
11a. = 15.4s
11b. = 427m
11c. = 200km/h

For full, see a friend or Ms.K.

Once finished, we went back to the first booklet we received titled, "Grade 12 Physics Acceleration & Relative Velocity" and went over page 6 - 9, doing the questions along the way. Don't worry if you weren't there, all the answers are stapled along with the booklet on page 11.

Page 6 extending to 7 is the lesson about relative velocity.

The concept of relative velocity can be a bit confusing, but with a little more understanding it can be easy.

It's the relationship between 3 different velocities, that can be different depending on the question. In the example included in the booklet, there are the velocities of a passenger on a train, the train itself, and someone standing on the ground watching the train.

To the passenger, who is walking to the front of the train, their velocity is +2.0 m/s.
Note: The + sign indicates direction, so if the passenger was walking towards the rear, the velocity would be -2.0 m/s.

The train's velocity, to the person on the ground, is +9.0 m/s.

We can calculate the velocity that the person the ground can see, or any of the three as long as we have any 2 velocities.

The formula that can be used is:

Vpg = Vpt + Vtg

Vpg = (2.0 m/s) + (9.0 m/s) = 11 m/s

p = passenger, t = train, g = ground.

Each velocity has letters in the subscript that are in relation to the objects in the question. Look at the bottom of page 6 for more details.

At the end of page 7 there is a small chart which can be filled out to find the answer.

So on the next page, 8 , there are two diagrams with a matching sheet of questions. The questions are pretty straight forward, but it's never bad to take a second check on the answer key.

For homework, we were assigned two things:

1) Page 10 of the booklet, for practice. (Answers included in the key)

2) A relative velocity sheet with 7 questions which you can get from Ms.K, if you don't already have it, which we will correct in class.

Well that concludes our day, and I will come back to fill in those answers, sorry everyone! Reminder, TEST ON THURSDAY! So study, study!

-Sakhone P

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