Hello grade 12's!
During Thursday's class, there were instructions given to us on the board and they were:
1. Finish the orbit lab on page 20 in your grey booklets. (It was due on Thursday at the end of class.)
2. Finish page 22 in the grey booklet.
3. Do problems 1-4 on page 160 in the green textbook. (Answers are at the back of the textbook)
4. Do problems 1-5 on page 172 in the green textbook. HAND IN ON MONDAY!

Here are the questions that were assigned from the textbook:
Questions on page 160:

1. An asteroid revolves around the sun with a mean (average) orbital radius twice that of Earth's. Predict the period of the asteroid in Earth years.
Answer: 2.8 years

2. From Table 8-1, you can calculate that, on the average, Mars is 1.52 times as far from the sun as is Earth. Predict the time required for Mars to circle the sun in Earth days.
Answer: 684 days

3. The moon has a period of 27.3 d and has a mean distance of 3.90 x 10^5 km from the centre of Earth. Find the period of an artificial satellite that is 6.70 x 10^3 km from the centre of Earth.
Answer: 88.5 minutes

4. From the data on the period and radius of revolution of the moon in Practice Problem 3, find the mean distance from Earth's centre to an artificial satellite that has a period of 1.00 d.
Answer: 4.30 x 10^4 km

Questions 1-5 on page 172 (Don't forget that these questions are for marks!)

1. Jupiter is 5.2 times farther than Earth is from the sun. Find Jupiter's orbital period in Earth years.

2. Uranus requires 84 years to circle the sun. Find Uranus' orbital radius as a multiple of Earth's orbital radius.

3.Venus has a period of revolution of 225 Earth days. Find the distance between the sun and Venus, as a multiple of Earth's orbital radius.

4. If a small planet were located 8.0 times as far from the sun as Earth, how many years would it take the planet to orbit the sun?

5. A satellite is placed in an orbit with a radius that is half the radius of the moon's orbit. Find its period in units of the period of the moon.

Enjoy!

February 9, 2011

Hey grade 12's, excuse my late post, I had trouble logging onto the student web mail on the Daniel Mac website.

During yesterday's class we discussed deriving formulas from position-time graphs. There is 2 types of graphs where you can derive equations from.

Graph 1:

This graph has a linear relationship and only focuses on one velocity meaning the velocity is constant. We use the equation v=d/t for this graph.

Graph 2:


This graph has a power relationship because it focuses on more than one velocity meaning the velocity is changing.

The formulas we derive in class are coming from the power relationships.
Example:


If given a graph like this, you can derive equations from it.
First find the area of the red rectangle, the formula for finding the area is (length)(width) which in this case is (velocity)(time).
Second find the area of the blue triangle, the formula for that is 1/2(base)(height) which in this case the base is acceleration and the height is (time)²
After completing that, you add the two together,
d = v₁t + (1/2)at² and you got your displacement formula!

**PLEASE REMEMBER** If given a question that starts off with something like this: An object starts at rest and it reaches a certain speed, it has two velocities not one. So don't use the formula v=d/t!!

You need to know how to derive equations from the graphs, so please read your notes or ask others or Ms K. for help if you don't understand! We also corrected the worksheet that we were given to on Monday, we also received a Study Guide and two other worksheets on Acceleration.

Next scribe is THOMAS, his post should be posted later on tonight. :)