THE END???

Hey guys!  I know that I haven't posted anything in quite a long time.  I just wanted to let you know that this could be the end.

When I say this, I don't mean that I will stop posting.  All I'm saying is that I'm not sure if I'll be posting much anymore due to the fact that I am no longer in a physics class in my school.  I can take it in my junior and senior year, but I'm not exactly sure about my life choices yet.

I just wanted to let y'all know this, just in case you were wondering why I suddenly disappeared.

I am still here, just not with the physics as of now.

Forces

Okay guys.  I believe that a huge apology is in order.  I mean, I haven't been blogging for quite some time.  I just want to let you know that I'm trying, and that we can have this blog, right here and now, be our fresh start.  A clean slate if you will.

So, without further ado, back to physics!

Lately, we've been learning about forces.  Truth be told we did start talking about acceleration, but that didn't work out so well.  Instead, our main focus has been centering around force diagrams and all that other stuff that relates to object in motion.  I'll try to sum it up for you all so that it isn't too long.

Types of Forces

Where, oh where to start? I guess it's fair to start off with the kinds of forces.  There are many types, such as tension and whatnot, but our two main focuses seem to revolve around what Mr. B calls "spooky" forces, and contact forces.  Spooky Forces are basically any type of force we don't really understand.  We know that it is doing something, but we don't exactly know how.  These include gravitational force, magnetic, and electrostatic.

By the way, Mr. Battaglia will not let us use the word gravity.  In his eyes, that word is basically like a swear word.  He even considered actually making something like a swear jar for any time you say it.  Instead, we must use the term Earth Force because it comes closer to following Mr. Battaglia's First Rule of Forces which states:  When naming a force, you MUST include the object giving the force and the object receiving the force.

The second main type, contact force, basically just has to do with anything touching or making contact with anything else.  This could include a hammer hitting a bowling ball (Yes, we did do a lab which involved smacking bowling balls with hammers in the gym).

Force Diagrams

I guess this leads me into Force Diagrams.  These are a little odd, but not too difficult.  Basically, you chose an object, let's say a bowling ball, and put it as a dot in the center.  Then, you describe, using arrows, all the forces acting upon that object.  For the bowling ball example, we would make the ball a dot in the center.  If we decided to make the ball speed up by hitting it with a hammer, we would draw an arrow to the right to indicate a force in that direction.  Then, we would also realize that the floor is pushing up on the ball to keep it from falling down (draw an arrow upwards) and that the Earth is also pulling down on the ball to keep it from floating away (draw an arrow downwards).

It's important that you realize that you can't just draw a random arrow.  It must be a certain length and in a certain direction.  Remember, the longer the arrow, the stronger the force.  If we were making the ball speed up, the hammer force (a contact force) would have to be stronger, so its arrow would be long.  As for the Earth force and the floor, those two arrows would be equal to show that the ball isn't moving up or down.   They balance each other out.

Another crucial point to bring up is the idea of a y-axis and a x-axis.  Like a normal graph, these two exist.  They can either balance out and equal zero (total), or one direction can be more or less than another.  In the bowling ball example, the y-axis balances out or equals zero because the Earth force and the floor force are equal.  However, the x-axis isn't balanced in the slightest due to the strong force to the right.

Now, what about a diagonal force?  There's no way we can only have up and down or side to side.  That is true, as far as we know right now.  Our class is actually working very hard to figure out the answer to this. Technically, it doesn't have to be diagonal at all.  A diagonal is actually just a horizontal and a vertical put together.  Think triangle and Pythagorean Theorem.  Two side of a triangle (or legs) can make a hypotenuse so to speak, so we can theoretically take a diagonal apart and turn it into a vertical vector and a horizontal vector, but who knows at this point?

Weight and Mass

We have just started this part of the section, so I don't know for sure, but I'll just put down a hypothesis to show that I am truly thinking.  As far as I know, I think weight and mass are definitely different.  Weight is the measure of how much the Earth or a body pulls on an object (the force exerted onto it).  As for mass, I believe that it is the amount of "stuff" in an object, like its atoms which are made up of protons and neutrons. That is why mass stays the same on whichever planet you are on, but gravity always differs.

Conclusion

I think I at least grasp what is going on. I am a little confused, especially when it comes to dealing with diagonals, but I'm working on it.  I definitely don't remembering doing all of this last year in physics, although I do remember weight and mass.  I think I am definitely liking the class a little better, especially compared to the beginning of the year.  All has been going okay, and I hope this continues.

Reviews For Midterms

Hey all you readers of physic blogs out there! I apologize for not writing a blog in what seems like forever. I've been so caught up in everything else, it's been hard.

Today, I've decided to post a blog to review for my midterms.  This will be a big help for me, as well as anyone else who really needs it.

Now, to get this out there, my teacher (whom I've never said before) is Mr. Battaglia, and he uses standards to grade us on how we did.  For this blog, I will go through some of the standards confusing for most people and I will try to give a quick summed up explanation of how it works.

Let the Standards Begin!

Converting Between Non-metric Units

To convert between metric units, it is imperative to understand that you need conversion factors before you do anything.  For example, you cannot convert from feet to yards unless you know that there are 3 feet in a yard.  

Now, to better explain this, I will need an example.  Let's say that you want to know how many yards is equal to 12 feet (This is an easy one so I can help you understand this better). For this example, we need to know that 3 feet is equal to 1 yard. To convert, there are 2 different methods.

1. Cross-Multiplying: To cross multiply, you are basically setting up 2 different fractions and multiplying diagonally.  For the example given above, we can do 12ft./x yd.. = 3ft./1yd.  We would then cross-multiply and come up with 12 = 3x.  Then, the answer is as easy as dividing 12 by 3, and finding out that x = 4yds.  When doing cross-multiplication, it is important to remember that you must put the same part of the fractions on the same part.  What I mean, is that, if you look at my example, you can see that both the feet parts are in the numerators, and both the yards parts are in the denominators.  You cannot have one feet part in the numerator and one feet part in the denominator.  Your answer will not come out correctly.
2. Dimensional Analysis: The second method to solve these types of problems is to do dimensional analysis.  To do so, we will use the same example shown above.  When doing dimensional analysis, you would also use fractions.  However, you set them up much differently.  This time, you would do 12ft./1 = 1yd./3ft.  Notice how one feet part is in the numerator and one feet part is in the denominator.  There is also no x (variable).  This time, instead of cross-multiplying, we would multiply like we would with any other fractions.You would do 12ft. x 1yd./1 x 3ft.  This time, since feet are in the numerator and denominator, the feet cancel, leaving you with 12yd./3.  Now, your answer is as easy as dividing, and it would come to the same answer of 4 yards.

Converting Between Metric Units

To convert between metric units, we do things a little differently.  This time it is easiest to just do KHDUDCM which stands for King Henry Drinks Unlimited Delicious Chocolate Milk.  This will help you when converting due to the fact that each letter stands for a metric unit. (Note: There are more metric units larger and smaller than these, so this isn't always the best way to convert).  The letters stand for Kilometer, Hectometer, Decameter, Unit, Decimeter, Centimeter, and Millimeter.

Let's get another example.  How many millimeters is equal to 5 meters?  To do this, all we are going to do is start at U (since meters is a unit) and move the decimal place 3 to the right due to the fact that you would move three on KHDUDCM scale to get from Units to Millimeters.  This would make your answer

5000 millimeters.

Note:  You can move right and left depending on which way you need to convert.  Going right tends to make the number bigger, and going left makes it smaller.

However, this is only the easy way.  It is also possible to use dimensional analysis with this when using even bigger or smaller units.

Converting Between Standard and Scientific Notation

For this standard, you kinda have to think about it.  Logic almost always plays some kind of a role in science.

Anyway, to convert between the two, we are going to have to slide the decimal place like we've done before.  Let's say our number is 5,000,000, and we want to convert to scientific notation.  Really, all we would do would be to slide the decimal place to the left until we get to the 5.  Then, we would count how many times we slid.  For this example, we slide 6 to the left.  Now, the question is, do we have a negative exponent or a positive exponent.  Well, we have to think about it.  Positive exponents make the number bigger, while negative exponents make the number smaller (if we were going from scientific notation to standard).  So, if we put this together logically, we can realize that we need to use a positive exponent, making our answer 5 x 10^6 or 5 E 6 (they mean the same thing).

If that was a little too confusing, let me explain going from scientific to standard.  Let's say our number is 

5 x 10^6.  I am purposely using the same example from above to help you understand.  Again, think about it. Positive exponents make a number bigger, so if we work opposite of what I showed above, we would move the decimal 6 times to the right, adding zeros and making the number bigger so that it is 5,000,000.

I'll do one more example.  This time, you want to know the standard from of 2 x 10^-3.  This time, you would notice the exponent.  This is your hint to tell you that you need to make the number smaller because negative exponents make numbers smaller.  This time, you would move the decimal 3 times to the left, making your answer 0.002.

Extra Help With the Different Types of Graphs

Our three types that we learned were position vs. time graphs, velocity vs. time graphs, and acceleration vs. time graphs.  Since I'm pretty positive that acceleration vs. time graphs will not be on the exam, I won't be discussing it (unless you need it).

Notes for Position vs. Time graphs:

• The slope is equal to the velocity.
• The y-intercept is the starting point.
• The x-axis (as far as I've observed) is the reference point.
• Displacement is equal to final position - initial position.

Notes for Velocity vs. Time graphs:

• The slope is equal to acceleration.
• The y-intercept is the starting velocity.
• Displacement is equal to the area under the curve.

Other types of graphs that we've done include:

• Linear: a straight line.
• Proportional: When x doubles, y doubles (or anything like that) and it goes through the origin.
• Direct: When x increases, y increases.
• Indirect: When x increases, y decreases.
• Inverse Proportional: When x doubles, y halves.

What the graphs look like:

• Quadratic: Looks like the letter "U" or and upside-down letter "U".
• Polynomial: Basically either a quadratic or a curvy line.\
• Inverse Square: The curve that never touches the x-axis and the y-axis, EVER.
• No Relation: Usually something like a scatter plot. (Scatter plots are graphs that are basically just graphs covered in dots).

Explaining the Meaning of Slopes

Slopes can be explained with a "for every" statement.  If your slope is 2 for a position vs. time graph (meters per second), your slope would be 2 meters/second (this would also be the unit for the slope in case you needed help with units).  To explain with a "for every" statement, you would say, "For every second time increases, the position increases by 2 meters."

Explaining the Meaning of y-intercepts

Y-intercepts can also be explained, but in a different way.  If  your y-intercept is 5 for a position vs. time graph (meters per second), you can see that your position is 5 and your time is 0.  To explain, you can say "At a time of 0 seconds, the position is at 5 meters.  This would be your starting position."

In Conclusion...

To end my blog, I just want to let anyone out there know that I really hoped this helped.  If you have any questions, you would like me to explain something a more, or you would like me to explain another topic, just let me know in any method (comments, email, etc.).  

Also, anyone out there who has to take this exam, I wish you the best of luck! You will all do fantastic!