November 14, 2011
Types of Forces

Applied Force (Fapp) – An applied force is the force that a person applies to an object.  It is any push or pull caused by a person.

 

Weight (FG) – The weight of an object measures how heavy it is.  It is caused by earth’s gravity pulling on the object.  It can be calculated using the mass of the object: FG = mg

 

Normal Force (FN) – The normal force is the force of a surface pushing back against an object.  It measures how much a surface (like the ground or a table) must push back to support the weight of an object.  For example, if you place a 2 lb book on a table, the table must push up on the book with a force of 2 lbs in order to support the weight.

 

Tension (FT) – Tension is a force that is being applied by a rope, cable, or string.

 

Friction (Ff) – Friction is a force that always opposes motion.  It is caused when two rough surfaces scrape against each other.  Even surfaces that seem very smooth have friction because of microscopic bumps and cracks on its surface.  It can be calculated using the normal force: Ff = μ FN. The symbol “μ” is the coefficient of friction.  It measures how rough the surface is; the larger the coefficient, the rougher the surface.

November 1, 2011
Sir Isaac Newton

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1. Where is he from?
2. Why is he famous?
3. List at least 3 contributions he made to physics.
4. What jobs did he hold?
5. Find something weird or interesting about him.

Here are some links to help you get started.  You can also just type his name into Google to see what comes up!

http://www.sparknotes.com/biography/newton/section1.rhtml

http://en.wikipedia.org/wiki/Isaac_Newton

http://www.biography.com/people/isaac-newton-9422656

http://www.bbc.co.uk/history/historic_figures/newton_isaac.shtml

October 11, 2011
Projectiles Launched at an Angle

Honors Physics Only

A water balloon is pulled back at a 45 degree angle and is fired with an initial speed of 15 m/s.  Determine the following about the balloon’s motion:

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a.    The range of the water balloon.

b.    The highest point reached by the water balloon.

Remember to list the givens in both directions, show the equation you started with, all of your work, and circle your final answer.

September 29, 2011
Projectiles Launched Horizontally

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A bear is at a local park, drowning his sorrows the way he knows best - by drinking a mug of honey.  Sad that his bear family has deserted him and that his bloodlust for humans has made him a fugitive, he slides the mug down the table in frustration.  The table is 0.9 meters high and the mug slides off the table horizontally with a speed of 4 m/s.  Determine how far away from the base of the table the mug hits the ground.

For full credit: list all the givens in the x and y direction, show the equations you started with, show all of your work, and circle your final answer with units.

September 15, 2011
Free Fall

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The PittFall at Kennywood drops riders from rest and they fall 76 meters.  Determine (a) how much time it takes to fall and (b) how fast the riders are moving at the bottom.  Assume there is no air resistance to slow the riders down.

For full credit, you must show the equation you started with, show all of your work, and circle your final answer.  Include units on your final answer.

September 12, 2011
How Fast Can Humans Run?

Click on the link below, read the article, and answer the following questions in complete sentences:

1. What do the authors mean by saying there is a “biological limit to running speed?”

2. With how much force do elite sprinters typically push off the ground?

3. What do the authors estimate is the ultimate top speed of a human?

http://www.sciencedaily.com/releases/2010/01/100122102843.htm

September 7, 2011
Acceleration

In class, we calculated Mr. Aul’s acceleration to be 3.3 m/s^2 and Usain Bolt’s acceleration to be about 1.1 m/s^2.  Use this data to answer the following questions: (Remember to use complete sentences!)

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1. Who would win in a race, Mr. Aul or Usain Bolt? Assume that both start from rest and at the same starting line.  Explain your answer.

2. Does it matter how far they run or does the same person always win? Explain how you know.

3. How would the rules of the race need to change in order to make sure that both runners finish the race at the same time? Explain your answer.

August 31, 2011
Displacement, Velocity, and Acceleration

The three major concepts of this unit are displacement, velocity, and acceleration.  The first concept, displacement, is very similar to distance.  Distance is simply a measure of how far an object has traveled.  Displacement is the distance between where an object starts and ends.  Those definitions sound similar so to illustrate the difference, read the example below:

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During practice, a football player runs from one endzone of the field to the other, turns around, and runs back to the fifty yard line.  The total distance the player ran was 150 yards (100 yards down plus the additional 50 yards on the way back).  The player’s displacement, however, is only 50 yards.  This is because when he stops, he is 50 yards away from where he started. 

The second concept, velocity, is very similar to speed.  Speed is a measure of how fast an object moves and can be calculated by dividing distance traveled by the time spent traveling.  Velocity is speed and direction.  To calculate an object’s velocity, divide its displacement by the time spent traveling. 

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The third concept is acceleration.  Acceleration measures how much an object’s velocity changes.  An object can accelerate in three ways: it can speed up, it can slow down, or it can change direction.  To calculate an object’s acceleration, divide its change in velocity by time.

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