UNIT BLOG REFLECTION


WHAT I HAVE LEARNED....


Newtons Second Law
We began the second unit by learning Newtons Second Law. Having found Newtons 1st law relatively straight forward, I was surprised to find the second more complex. Not only did it deal with two aspects, but also involved a formula. For me as a learner, the simple mentioning of a "formula" often raises red flags. However, through practice and studying, I have wrestled with the material.
Newtons Second Law: Force is proportional to acceleration and mass is inversely proportional to acceleration. 
So what does that mean? Although I have the basic definition down, breaking this down and really understanding it is another story. From what I gathered, because they are proportional, when force increases, so does acceleration, and when force decreases, so does acceleration. Contrasting this process, because mass is inversely  proportional to acceleration, when mass increases, acceleration decreases, and when mass decreases, acceleration increases.
However, still, what does this mean?
I like to think of it like this. If something is has an extremely strong force on it, it is going to move faster, thus gain more speed, and essentially have a higher acceleration rate.

In this picture, the explosion is causing batman to fly forward at a very fast rate. It is shown in this picture that a large acceleration will mirror a large force.




When dealing with mass, things are slightly more complicated as acceleration is no longer proportional but inversely proportional. I like to think of it as bigger people tend to move slower, and it is also harder to push/lift large objects than it is to do so with small objects.

vs. 

Bart can move faster because he has less mass!

Formula:

Acceleration=(net)force/mass

Applying Newtons 1st law to a problem:

A 10 kg box is being pushed with 5 N to the right and 45 N to the left, what is the box's acceleration?

solution:

A=40/10

A=4m/s^2

Newtons 2nd Law (in relation to lab)

I think that the major aspect of this lab was integrating concepts from unit 1 and unit 2. The equation of a line. Last unit, this section was by far the most challenging for me. Therefore, when I saw that it is repeating itself in this unit, I was a little dismayed. However, through Hunter's podcast, I was able to gain a much better idea of what this concept really is. Ultimately, the equation used for this is a=fnet/mass, this can be translated to a= fnet x 1/mass, which is completely compatible with the equation of a line. The equation of a line is y=mx+b.

What Hunter talked about in his podcast was how we can ignore b because it is too small to be significant. Additionally, he talked about how m is always what is kept constant, x is what you change, and y is what you solve for. 

Mass vs. Weight 

Before this unit, I really did not know that there was a big difference between mass and weight. However, when applied to physics, the difference is huge. I think that most importantly, weight acts as a force. Mass contributes to weight as mass and gravity are multiplied to equal the weight. 

How does weight act as a force?

Weight acts as a force because the force of gravity pulls objects down at different rates depending on their forces, this process is weight.

formula:

Weight=mass x gravity

KEEP IN MIND: GRAVITY IS ALWAYS 10 N (unless dealing with labs, in which case it is 9.8)

Practice Problem:

What is the weight of a baby that has a mass of 2 grams?

Weight= mass x gravity

w=2(10)

w=20 N 

*ALWAYS USE NEWTONS WHEN DEALING WITH WEIGHT*

Applying Sky Diving to Newtons 2nd Law

One of the major things that Ms. Lawrence stressed to us at the beginning of the year, is how her goal is for us to be able to apply physics to real life situations. The sky diving section of this unit is a perfect example of this. When skydiving, as soon as you jump off the plane, your velocity begins to increase. However, eventually you will reach terminal velocity which is the maximum velocity a certain object can reach. When terminal velocity is reached, velocity is decreased as equilibrium becomes present. Additionally, netforce and acceleration decrease because the object is reaching equilibrium. 

How do we know this?

NEWTONS 2nd LAW! acceleration decreases because for decreases, we know this because of Newtons 2nd Law which states that acceleration and force are proportional!

When the skydiver reaches terminal velocity, net force and acceleration will equal 0. 

Parachutes

When the parachute opens, things become much more complicated. The terminal velocity is suddenly broken as the parachute opens, immediately slowing down the skydiver. So what does happen when a parachute opens?

Because of the dramatic change of the process of the parachute opening, it causes acceleration and netforce to actually increase in an opposite direction. Because of this, speed decreases because of the force and acceleration pulling it upward. Air resistance also decreases because it is proportional to speed. However, eventually, the skydiver will reach terminal velocity. This terminal velocity will be slower than the one before because over the negative acceleration and force. Also when terminal velocity is reached, force, air resistance, and acceleration will equal zero. 

FREE FALL

If an object is in free fall, the only force acting on it is gravity. Therefore, there is no air resistance. Just the force of gravity. Also, in free fall, acceleration will always be consistent and remain 10 m/s^2. 

IN FREE FALL, WEIGHT DOESNT MATTER!

(and neither does mass!)

Instead of writing out practice problems here, I think that this video goes into deeper depths of freefall, also it is able to portray the problem visually.

When an object is falling DOWN it is the exact same concept except instead of throwing it up, you are throwing it down. In fact, it is simpler when an object is being thrown straight down because it is being thrown from rest.

Example Problem:
Why is it that a led ball and ping pong ball hit the ground at the same time when dropped off of a ping pong ball, yet hit the ground at different times when dropped off of a building?
Because the two balls have different masses, they will have different air resistances. When a led ball is being dropped off of something it will have to increase speed to equal the force of air resistance in order to achieve equilibrium. However, for a ping pong ball, air resistance is less, therefore it will not need to go extremely fast to balance the two forces. Because of this, the led ball will go faster. However, when dropped off of the short distance of a table top, the balls do not have time to reach their terminal velocity, therefore will hit the ground at relatively, the same time.

Falling at an angle
The final concept that we studied in this unit is falling at an angle. I also found this section difficult as we incorporated a new level of match that involved included right triangle problems. We also learned how to distinguish between finding the horizontal and vertical velocities and distances. For horizontal we use the formula v=d/t and for vertical we use d=1/2gt^2
When an object is falling, everything depends on HEIGHT!
Additionally, we also learned to find perfect right triangles to help with our answers. The triangles we learned to look out for are 45, 45, 90 triangles, 30, 40, 50 triangles, and 10, 10, 10 root 2 triangles.

WHAT I HAVE FOUND MOST DIFFICULT....

Because I also struggled with it last unit, I found the equation of a line concept challenging. However, through watching the podcast on that topic and seeking extra help, I definitely have a better understanding now. I also found falling at an angle difficult, however similarly, seeking extra help and watching the podcasts were very helpful.

PROBLEM SOLVING SKILLS, EFFORT:

I think that I have certainly put forth my best effort throughout the unit. I am almost positive that I have all the homework completed. I think that I could definitely pay more attention in class through actually working problems Ms. Lawrence puts on the board rather than copying them down on my paper without thinking it through. Later, when I look at the examples from class they do not make sense because I do no remember how I completed them. However, I am becoming more consistent with drawing pictures and showing my work which has helped me catch careless mistakes and become more accurate with my answers. I think that I also attempt to be as creative in this class which aids in my understanding. With our podcast, we tried our best to make it interactive and interesting in order for people to pay more attention to it. My physics confidence is certainly growing as I progress as a learner, and our class progresses as well!


REAL LIFE?

In reality, the obvious answer for this question is skydiving. Of course we know that people go skydiving all the time. However, what we do not catch as easily is that everything we learned in this unit can be applied to the real world. For instance, free fall. We drop things of buildings all the time. Also with directional falling, we do that as well! (baseball, throwing something to someone, dropping something from a plane, hanging time). Newtons 2nd law can be applied as well.

OVERALL
I enjoyed this unit! It was certainly more challenging, however it was interesting!