Because we have finished the required curriculum for this year in Science 9, we are now in the process of reviewing the curriculum for the final exam.

Here are the questions assigned for Monday, May 7 2007:

1. Which is the largest planet?

Jupiter

2. Which is the smallest planet?

Pluto

3. Which planet is a similar size to the Earth?

Venus

4. Is Mars larger or smaller that the Earth?

Smaller by 6,000 Km (diameter)

5. Which planets have ring systems?

Saturn and Uranus

6. Which planet has the most moons?

Jupiter, which has 63

7. Around which planet is the moon Mimas?

Mimas orbits around Saturn

8. To which planet did the Huygens-Cassini probe go?

The probe went to Saturn, flying by Jupiter, Venus, Earth, and some of Saturn’s moons on the way

9. On which planet is the “Great Red Spot”?

The “Great Red Spot” is located on Jupiter

10. In 1994 on July 16-22 fragments of the comet Shoemaker-Levy hit the surface of which planet? How big was the largest impact image compared to the Earth?

The planet that the Shoemaker-Levy comet broke up into was Jupiter. Some impact craters were so large that the Earth could have easily fitted inside them.

Pictures (click to enlarge):

Jupiter’s “Big Red Spot”:

Surface of Mars, taken by NASA’s Spirit rover (taken January 6, 2003):

Surface of Venus, taken by Russia’s Venera probe:

Here are the pictures of the pig heart we dissected today.  You can click on the picture to enlarge it.  If you would like the full resolution version of the pictures, email me at jamesmack1@gmail.com with the picture number:

Here are the questions that were assigned 3-04-07.

homework-3-04-07.doc

For the past few days we have been studying the body and its various functions. Today we were told to make a possible diet for my Science 9 teacher Mr. Tilcock using the National Heart, Lung, and Blood Institutes’s interactive menu planner. My possible diet for Mr. T is contained inside the screen shot below (click to enlarge):

In today’s class we learned about specific heat capacities and how to calculate them. The specific heat capacity is the amount of heat transferred when the temperature of 1.0 kg of the substance changes by 1°C Here’s the formula and an example:

The formula:

Energy

———-

Mass x Temperature Change

An example:

If it takes 8000J to heat 100g of oil from 30°C to 70°C the formula (with relevant values inserted) is:

8000 J
——-
0.1 kg x 40°C
=
20,000 J (kg C°)

An inclined plane is a plane surface set at an angle, other than a right angle, against a horizontal surface. The inclined plane permits one to overcome a large resistance by applying a relatively small force through a longer distance than the load is to be raised. In civil engineering the slope (ratio of rise/run) is often referred to as a grade or gradient. An inclined plane is one of the commonly-recognized simple machines. Paragraph courtesy of Wikipedia.

Does using a ramp reduce the amount of work needed to raise the object? Explain your answer.

Using a ramp makes lifting easier but it increases the work.

Why do you think people use ramps to work?

Because it is quite a bit easier to use a ramp than lifting something outright.

Describe some examples in everyday life when people use ramps to help them to do work.

Wheelchair ramps, loading ramps, mountain biking trails and walking trails.

Today in class we talked about radioactive decay. Nearly all elements have radioactive isotopes. This means that the atom is unstable, and will eventually decay by emitting a particle, transforming the nucleus into another nucleus, or into a lower energy state. Decays happen in half-life’s. When a half-life passes (5730 years for carbon-14) only half of the material that was there in the start still exists. Here’s an example: Imagine carbon-14 was just made. At its half life, its mass will reduce to half the size it was when it was created. So, in turn, at the next half life carbon-14 would be only 25% of its original mass because at each half life, half the isotope has vanished. A chain of half-life’s occur (each depleting 50% of the isotope every half-life) until a stable nucleus is reached. When that stable nucleus is reached, many uses of radioactivity become unusable or unreliable, such as carbon-14 dating.

Carbon-14

Carbon-14 dating is commonly used in items that are 1,000 to 40,000 years old. This is how it works:

As the Earth’s atmosphere is bombarded by cosmic radiation, nitrogen is broken down into carbon-14. It falls through the atmosphere and is picked up by Earth’s atmosphere and spread around. Because it reacts identically to carbon-12 and carbon-13, carbon-14 becomes attached to plants using photosynthesys and becomes part of their molecular makeup. Animals eating those plants in turn absorb carbon-14 as well as the stable isotopes. This process of ingesting C-14 continues as long as the plant or animal remains alive. When the animal or plant dies, the carbon-14 decays, but because they are not radioactive carbon-12 and carbon-13 stay whole. By measuring how much of each isotope there is in the item in question, the age can be determined.

A very good calculator for finding values of half-lives is located here.

Today we talked about radiation. There are three main types of radiation: alpha, beta, and gamma.

• Alpha radiation is so weak that it cannot penetrate a piece of paper, and is a helium nucleus. This type of radiation would have to be ingested to be lethal. A recent incident involving this type of radiation, the poisoning of Russian ex-KGB agent Alexander Litvinenko, was caused by alpha radiation from the element Polonium-210.
• Beta radiation is capable of passing through a piece of paper, but would not be able to pass through much more than that.  Beta radiation can penetrate farther than alpha, but not as far as gamma radiation.  It is also a particle.
• Gamma radiation, on the other hand is not a particle and has a much greater radius than alpha and beta radiation. Alpha radiation would only be able to kill you if it got inside you, whereas beta and gamma radiation would be able to kill you externally. Radiation kills by depleting the body’s bone marrow and white blood cells.

Some good shields against radiation are lead and water. Water is the most common shield, and is used in nuclear reactors.

In class today we talked about isotopes. Isotopes are elements that contain different numbers of neutrons. All elements contain at least one isotope. A very good site to learn more about this is the Berkeley Laboratory Isotopes Project, located here.