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!

Car Crashes

This week's physics class, as far as I'm concerned, was the most fun yet.  Even my friend said that she now officially loves physics because of this class.  I mean, we did get to "blow things up."

My teacher said that this week, instead of having another discussion on motion before the Thanksgiving break (even though he does agree that we need more), he decided to let us "make" action movies. Apparently he loves them, so he came up with three different scenarios for us to chose from.

The Rules

My teacher decided on giving us a set of rules so that this wouldn't be too easy.  They are as follows:

1. You only get one shot at it, and if you screw up, "you'll never work in this town again!"
2. You cannot test it out beforehand.
3. You must follow your scenario exactly, meaning that, if it gives you measurements, you must use them.
4. Your two cars will be at different speeds.
5. You cannot run both cars at the same time.  Only one can run.  Otherwise, you will be disqualified.
6. If you make the two cars crash and you follow the scenario, you will "have your people call his people."

Our Scenario

My group and I decided to chose scenario number 1.  In this scenario, we had to have two cars come at each other from two different directions.  They MUST be 2 meters away from the crash point, but we get to decide at what time we should start each car.

Of course, one car was slower and one car was faster.  To make it a bit more comical, we decided to name the slower car Grandma and the faster car something about speed.  I can't remember the real name we came up for him, except for the fact that I called him Speedy McSpeedson.

Our Process

To find out how fast each of the cars went, we decided to measure how much time it took for each car to travel 1 meter.  We then doubled it to see how much time it took for 2 meters.  For each car, we actually recorded the time 5 different times to make it more accurate, and then we found the average.

• Grandma: 1 meter= 5.6 seconds, 2 meters= 11.2 seconds
• Speedy McSpeedson: 1 meters= 4.26 seconds, 2 meters= 8.52 seconds

From this data, you can obviously tell that Speedy was faster than Grandma.  However, we actually got stumped on what to do next. Eventually, we figured out that all you had to do was subtract the two times to find out when to release the second car.  We did 11.2- 8.52 and found that the answer was 2.7 seconds, meaning that we needed to release Speedy McSpeedson 2.7 seconds after we released Grandma.

In the End...

In the end, we ended up succeeding and causing the cars to crash.  It felt good to have gotten it right.  I'm very happy that I got to work with my group.  They all did a great job trying to figure out the answer, and everyone in the class, including myself, had a great time.  Personally, I would like to do another activity like this one again.

Another Worksheet... Darn

Hello everyone out there listening, or I guess reading, if you want to get technical.  This week, just like the last one, I had to miss class.  You can blame my orthodontist for this one, but of course, missing class meant missing another discussion, and I really don't like missing discussions.  I mean, those things contain some valuable information which now, because of my appointment, I will never know.  Really, all I took out of this week was a fairly easy fiesta (quiz) and a worksheet.

Fiesta

You all know how it is.  When you think something is easy, you usually end up doing horrible, especially in a class like math.  However, I seemed to understand the fiesta.  After all, it was on Position vs. Time graphs which are easier for me to comprehend anyway, so overall I think I did pretty good.  I've got my fingers crossed.

Worksheet

The worksheet was called Constant Velocity Model Worksheet 4: Velocity vs. Time Graphs and Displacement.  We were told to do the worksheet with our tables and discuss any questions we had. Again, like the fiesta, I didn't find this to be too hard, and I found it very helpful to work and discuss in a group.

Basically, the worksheet went through making motion maps, writing written descriptions of the motion of objects, making Position vs. Time graphs, making Velocity vs. Time graphs, writing mathematical expressions for motion, and determining displacement.  However, there were three other things which still kind of have me confused; the area under the curve, average velocity, and average speed.

The Area Under the Curve

The only reason I understood this part of the worksheet was because I had actually watched a video on my own about it.  The area under the curve is basically the area of the "squares," I guess, on a Velocity vs. Time graph.  You would basically do length times width or base times height or side times side (whichever you prefer) to get the area of each little rectangle, and then you would add them all together to find the total area under the curve.  Supposedly, this comes out to the displacement of the object, so this could actually be quite a handy way to find it.

The graph above is actually the Velocity vs. Time graph from the worksheet.  If you notice, there are three rectangles, and if you were to find the area of those and add them, then you would find the total displacement.

If you were wondering what you do for the "non-rectangle" parts, you basically do nothing. Technically, you would find the area of them too, but since it isn't a rectangle, it only has one dimension, so its area is technically 0.  Basically, there is no need to find it because it is always 0.

Average Velocity

For this one, I must thank my group for helping me figure it out.  To find average velocity, you first need to know what velocity is.

Velocity is basically speed with direction included.  This hints that velocity can be negative.  If you used the graph above, and you were asked to find the average velocity form t=4 to t=8, you could do so easily.

All you do is take the firs velocity at t=4, which happens to be 3 meters/second, and add the velocity at t=8 which is -5 meters/second. So, 3+(-5)= -2 meters/second.

You would then divide by the amount of time passing to get the average.  This comes out to be 4 seconds, so you would do -2/4 which is equal to-1/2 meters/second.

Average Speed

Again, I must thank my group for helping me figure this out.  However, we still aren't 100% positive on this one, so I may be wrong in what I am saying.  To find average speed, you need to know what speed is.

Speed is distance divided by time.  There is no mention of direction in the definition, so we know that speed cannot be negative. 

If you were asked to find the average speed from t=4 to t=8, you would take the two velocities mentioned before and make them positive.  You would get 3+5=8 meters/second, and you would then divide by 4 to get 2 meters/second.

Reflection

Again, I am not positive on the average speed portion of this worksheet, but I am fairly certain about the other parts.  Truthfully, I wish that I hadn't missed two days of class.  It really makes me feel behind, but I guess I have to embrace the confusion like they always say.  I hope that I can get back on track next class. Although, I know for sure that all I can do is try my best.

Lists of Motion Info

This week, sadly, I was only able to get one class worth of information.  Today in fact, was supposed to be my second day for physics this week, but of course I had to be absent.  I really hope that I didn't miss too much, and that our fiesta (test, quiz thing) wasn't too hard.

Anyway, this week, we continued to focus on motion.  However, we definitely got more in-depth on different parts, especially this new term called displacement.

Displacement is the change in position, but it is NOT I repeat NOT distance, however close the two words may sound.  I mean really, why start them both with the letter D?  That just makes things more confusing for everyone.  To explain, I should probably review the words that could possibly confuse me more and show how they are different.

The Differences

1. Distance

• Distance is the total amount traveled.  For example, if you walk 9 steps to the right, 3 steps back, and 1 step left, your distance is equal to 13 steps.
• Distance compares two (or more) locations.  For example, if you travel from point A to point B, your distance is the length between the two.

2. Position

• Position is the point you are at at one point in time.
• To find your position, you use your reference point.
• There is only one way you can get to the position that someone else is in right now.
• Position deals with direction.
• Position can be negative or positive depending on the direction relative to the reference point.
• Position is a single point, like Point A. 
• To sum it up, position is the distance from a reference point (with direction) at one point in time.

3. Displacement

• Displacement is the change in position.
• Displacement has direction associated with it.
• It can be negative or positive.
• Displacement is where you end up relative to your starting point.  For example, if you go on a long journey, the only thing that matters for displacement is where you end up and how far that end point is from where you started.
• In another sense, if you start from point A, then walk to point B, then walk to point C, displacement is only how far you are from point A to point C.
• Displacement uses the starting point, not the reference point.
• To sum it up, displacement is the change in position relative to the starting point, not the reference point.

Putting Things Together

So now that you know that these three terms are obviously different, let's relate them to something else... like... Speed and Velocity!

As a class, we deduced that displacement seems to go more with velocity, while distance goes with speed.

Speed= Distance/time

Velocity= speed with direction= Distance/time with direction= Displacement/time

Reflection

I realize that this blog is kind of a mess, but that's a little like how I feel right now.  Missing today definitely didn't help, but it couldn't be helped.  I'm still pretty confused, although a little less so, and I hope that my understanding will increase next week.  However, I will have to take my fiesta next week, and I am a little worried.  I guess all I can do is try.

All Parts of Motion

Position vs. Time graphs, Velocity vs. Time graphs, and Motion Maps.  Anyone know what those are? Anyone?  Well I'm not sure I know either.

This week, we learned about the three things mentioned above, but of course, my mind jumped from certainty to confusion and back again, as I tried to figure out how they worked.  I felt so dumb, especially because I had gone through all of this last year, with the exception of motion maps.  I started off only remembering the names.  Then, there was a flash of light and I instantly remembered what they were, but then I forgot how to draw them.  Then, there was yet another flash of light as I remembered, but now I'm not positive I'm right.

My class seems to be very confused, and that is not boosting my confidence.  Usually, I have a pretty good grasp on what's going on, and I still kinda do.  It's just that we haven't really figured out exactly what they are, and of course our teacher won't tell us.  We have to learn it for ourselves, and I guess that does make sense to some degree.

My First Understandings

This week, we did a lab that dealt with Position vs. Time graphs and Velocity vs. Time graphs.  We were given one of them, and we had to figure out the other.  To do so, we were given a motion sensor and a computer.  We had to try to mimic the graph given, and then draw the other, so if we were given a Position vs. Time graph, we had to do a "walk" in front of the sensor to try to make that graph.  At the same time, the computer would make the other graph, in this case a Velocity vs. Time graph, and we would draw it on our packet.  Then, we would put our "walk" into words, and then draw a Motion Map.

Off of this lab, my understandings were:

• I have no idea how to do a motion map.
• Position vs. Time graphs are easier to do than Velocity vs. Time graphs.
• Your motion sensor is the reference point. (definition in my other post http://ittakesphysics.blogspot.com/2013/10/movin-around.html )
• When you walk towards the motion sensor (reference point), your Position vs. Time graph goes down towards the x-axis, and when you walk away, your Position vs. Time graph goes away from the x-axis.
• If you go at a constant speed, your slope for your Position vs. Time graph is constant.
• If the line is flat on a Position vs. Time graph, your position is constant.
• I seem to only understand Position vs. Time graphs.
• I think I did the lab wrong...

Worksheet Understandings

Then my teacher decided to give us a worksheet called Constant Velocity Particle Model Worksheet 2: Motion Maps and Velocity vs. Time Graphs. Yep, it's a mouthful, but it helped me out greatly.

Off this worksheet, I found out that:

• When an object moves in a negative direction, the velocity is shown as a negative velocity on a Velocity vs. Time graph and when moving in a positive direction, it's the opposite.
• When an object isn't moving, the velocity is 0.
• When an object moves at a steady speed, the velocity is a constant, straight line.
• If the object starts off in one direction at a constant speed and then changes its direction, but still goes at the same constant speed, the graph would look like this:
  
  
• If the object is going the same speed, but in a different direction, the line needs to be at the same number, but negative.
• If the object changes speed, you draw a line straight down because it is changing its velocity instantly.
• This website helped: http://www.physicsclassroom.com/class/1dkin/u1l4b.cfm

Motion Map Understanding

Our teacher then emailed us a reading on motion maps to help us do them on the worksheet. It's http://daisleyphysics.com/worksheets/mmap.pdf 

I learned that:

• Motion maps look like this:

• If an object moves at a constant speed, the arrows have to be the same length.
• To draw one, you must put a point for each time marked.
• The slower the speed, the shorter the arrow, and the faster the speed, the longer the arrow.
• If an object doesn't move, or stays in the same position, you use dots for each amount of time, and since the object doesn't move, the dots stack.
• From the picture above, each notch on the line is a meter.  For the first arrow, it starts at 0 meters.
• If an object turns around, the arrows do too, and they can go over each other because they head back to 0 meters.
• If an object moves in a positive direction, the arrows go to the right, and if the object moves in a negative direction, the arrows go to the left.
• I am still a little confused.

Reflection

This week, I was more confused than I have ever been so far in the year.  However, we still need to have a real, in-depth discussion on it, and I think that will help.  I am doing good in my groups as well, and I am still participating and helping out.  I also feel like I only talk when I need to, at least that's what I try to do.  I am trying not to talk too much, and I am trying not to talk too little.  I guess it's all about making sure I understand, and that is why I have decided to ask questions to clarify certain things that we talk about.