Meter Stick Blog

     The meter stick, when it is balanced on the table, does not have a torque because each side of the meter stick has a torque, but in opposite directions (clockwise vs counterclockwise), so they cancel out.  The center of gravity of the meter stick changes when you add the 100 gram weight, in order to ensure that both sides (when balanced) have the same torque.
     To figure out how much the meter stick weighs, we (me and Manuel) measured where the new center of gravity was with the weight, and it was 24.4 cm from the edge of the meter stick.  The center of gravity for the meter stick was 50.6 cm.  We had to find the torque of one side of the meter stick, so we used the one with the weight on it, where we knew both the force downward (9.8 times .1) and the lever arm (.24).  Using those numbers, we got the torque as .239 N.  We then plugged that number into the other side, with the equation .239=(.506-.244)(Force), with Force being the weight of the meter stick.
     With this equation set up, all we had to do was solve it, then convert the answer from .912 Newtons, to grams, which gave us the answer of 92.85 grams.  The actual weight was 92.1 grams.
   

(Labelled drawing in progress)

Torque Resource

The video is from a series that contains tutorials on various different subjects, namely Khan Academy and this one is on the subject of torque.  It is really just a video that will teach you about torque through use of a sort of digital blackboard to illustrate the lessons that the narrator is giving.

Rotational Inertia resource

This video shows a spin from an ice skater that, when she tucks in her arms and legs, reaches up to over 300 rpm.  I thought this was a very good video to show off rotational inertia, as it is very clear that she is able to reach those speeds only after tucking in her arms and legs.

Unit Reflection Unit 3

Unit Blog Reflection

A. In this unit I learned about the concepts of gravity and momentum.  This includes vectors, action/reaction pairs and conservation of momentum.  Gravity is the force that everything gives off, and it causes everything to interact with everything else.  The formula to determine the strength of gravity is F=Gm1m2/d-squared.  Momentum is the force an object has, you calculate momentum with mass times velocity.  Vectors are lines that show the direction and magnitude of an object’s projected path.  Action/reaction pairs are, well, everything, because everything is affected by everything else and Fa     = -Fb  .  Conservation of momentum states that momentum never disappears, it is just transferred into different objects. 

The things that I have found difficult about this unit are all of the particulars for how you answer each problem, especially when it comes to vectors.  If you mess up on answering any part, you start losing points.  I haven’t overcome these difficulties quite yet, but when I do it will be because of excessive repetition.

My problem solving skills, I feel, are fairly good, apart from the situation I described last paragraph.  My effort towards homework could be much better, I will work on that in the future.  My effort in activities is around the average, the activities themselves are very interesting, and the mathematics aren’t too complicated.    My effort towards blog postings is average as well, given that they are often more fun to do than regular papers.  I have been learning, although some stuff I still need to work on, but I do know most of the material.

B Momentum is one of the big things that physics connects to everyday life, whether it’s a car accident or sailing a boat across a moving river, momentum in one form or another governs the behavior of such objects.  Gravity is an even more universal concept, as without it the universe as we know it would stop existing.

Blog Reflection Unit 2

Blog reflection

In this unit I learned about Newton’s second law, as it pertains to throwing objects in the air and telling their speed ,acceleration and how far they have gone.  If an object is thrown straight upwards (neglecting air resistance) it will decrease in velocity by ten m/s for every second, due to that being the pull of gravity.  If you throw an object upwards at an angle, it’s velocity is the product of the equation a squared + b squared = c squared, with “a” and “b” being your vertical and horizontal velocities, respectively.  I also learned about how vertical distance is the only thing that affects how long you fall for, no matter how fast an object is going it will still hit the ground at the same time as an identical object dropped at the same moment.  You can determine how long an object spends in the air by using the D=1/2 A(t squared) formula, and substitute gravity for “a” and the distance for “D”.  You can then find how far the object traveled horizontally with d=at.  To introduce this concept, we were shown a video from the Mythbusters, who shot a bullet and dropped a bullet of the same caliber at the same time and watched in slow-motion as they hit the ground at the same time.  

The thing that I found difficult about this was not the mathematics that we were doing, it was simply trying to get my head around the concepts that we were learning, such as “it doesn’t matter how fast something is going, vertical distance is all that matters when you a determining how long something falls for.  I overcame these difficulties with looking at real world examples, and accepting them as the truth.

I do try to expend as much effort as I can in class, but I am distracted easily so it is difficult sometimes.  My effort towards blog posts especially needs some work, as I often simply forget to do them.

I don’t think I am very persistent in trying to solve a problem in physics, if I don’t understand by my second or third reading then I will likely skip it and move to the next problem.  I am fairly confident in physics at this point, due to the fact that I believe I understand all of the material that we go over.  Taking time doing the problems is a bit difficult for me, as I do like to do them quickly and get them done so I can do other things, but that is a problem I could easily fix if I am making a large amount of careless mistakes.  

My goal for the next unit is to make sure I have all of my blog posts in  on time and to make sure to not have any work late.  To accomplish this I will take more care in filling my planner,  and also to take more care in looking over my planner every night before study hall, when I still have internet.

Newtons Second Law Resource

This is about a pilot explaining gravity forces on someone while they are in a jet.  This shows off Newtons Second Law in a vey interesting way, because it shows not only the equations, but also what happens if gravity is changed.

Blog Reflection

        In this unit I learned about the most basic rules governing movement, such as inertia, which is the property of objects that any object that is in motion wants to stay in motion and any object at rest wants to stay at rest.  I also learned that velocity is a factor of both speed and direction, and if an object has a constant velocity than it must be at equilibrium, which is also synonymous with saying that it’s net force is zero.  Net force is the total amount of force acting on an object, so if I push with 50 newtons is one direction and someone else pushes with 50 newtons in the opposite direction the net force will zero.  Acceleration is when the net force is not zero, which means that the force pushing the object is enough to overcome the objects inertia and the friction of the object.  Acceleration can be achieved through multiple methods, but the one that we looked at in class was if a ball rolls down a ramp, and we discovered that it doesn’t matter if the acceleration is increasing, decreasing or constant the objects speed is always increasing.  The acceleration of an object can be measured with the formula A=V/T, for acceleration equals velocity over time.  Velocity can be calculated with the formula V=AT, for velocity equals acceleration times time.  Distance is measured with D=AT^2, for distance equals acceleration times time squared.

The most difficult thing about what I have studied is keeping all of the formulas straight in my head, sometimes I get them confused.  Also, some of the concepts that we look at are very confusing, such as the concept of friction always giving off equal force to that the object is being pushed with.  I overcame these difficulties by assuming that it is true at first, and then spending a while to work over the concepts in my head until I get an idea of how it would work out that way.  The thing that made the lightbulb click was when I realized that equilibrium is the same whether or not the object is moving, so any net force greater than zero would accelerate the object rather than keep it moving.  My goal for the next unit is to get an A by doing all of my assignments on time.

There are many connection is between what we are studying and real life, because what we are studying is the rules that govern real life.  History is a much more interesting comparison, because inertia can apply to nations and governments just as much as it applies to bodies in motion.  For example, a nation at war, once it has started winning it is very difficult to turn around the course of the war, which could be an example of “inertia” applying to war.  Another example is politics.  If a motion or a candidate starts gaining popular support, based off of what I know it will take an effort to turn the process around.  Another example of nations trying to continue doing what they are currently doing is that the U.S. keeps going to war in other countries.