Unit 3 Blog Reflection

Things I learned this unit:
-Action/Reaction pairs/ Newton's 3rd Law:
     In this section of the unit we studied Newton's 3rd law (every action has an equal and opposite reaction) and how it works in accordance with objects in the world. For something to be classified as an action/reaction pair they have to use The Same verb  and The Same Two objects acting in opposite directions. For example: apple pushes down on table, table pushes up on apple. Not: earth pulls down on apple, table pushes apple up. We also did a discovery lab for this section that showed us that when a mack truck hits a smaller car, the force experienced by both of them is The same.

-Tug of war/ Horse and buggy:
      This section of the unit came directly off of Newton's 3rd law in how we applied it. Take for example a tug of war match. In this match merely pulling on the rope with your arms will be useless as the rope/ other team will pull back on you with equal and opposite force, yielding no net gain of ground. To win a tug of war match you must be able to push harder on the ground as seen when we had the boys put on socks and girls have shoes on. The way to answer a horse and buggy/ tug of war problem is by first addressing the action/ reaction pairs seen in the problem (ie forces on rope, forces on ground w/ winning team pushing harder on the ground therefore the ground pushes the winning team further and or stronger). Next you have to explain how the object or team that pushes harder on the ground will be pushed harder by the ground and will therefore have more force. This is one of the big problems of the section and will undoubtedly appear on tests and exams in the future.

-Adding Forces/Vectors at angles:
     In this section we addressed the fact that when vectors are at different angles from each other we cannot simply add the components, but rather we must find the resulting force of different components, and then use the Pythagorean theorem to find the real net force. This in part explains why a box will slide down an inclined surface. As gravity acts only downward, there must be a support force. However this support force must be perpendicular to the surface that the box is on. When we use our box method for finding a resulting force we find that the fnet points down the slope. Another problem that we encounter in this section is one involving the tension of multiple ropes that a ball or object hangs from. To do this we use the force of gravity to find a support force upward. Then we have a line connecting the tip of the arrow and intersecting one of the ropes. Note that this line must be parallel to the other rope! Then we shade in the resulting areas that have been cut off by these lines. The rope with a longer ftension will be more likely to break.

-Gravity and Tides:
     In this section is the concept of universal gravitation. This means that every object with mass in the universe attracts every other object with mass in the universe. The universal gravitational force equation is as follows: F=G(m1)(m2)/d^2 where G= 7.0x10^-11. It is important to note that the Distance is Squared. To solve one of these problems we plug in given information, then separate the x10^ etc... from the other numbers. We solve both of the separate information sets by adding exponents when multiplying, subtracting exponents when dividing, and multiply exponents when raising an exponent to another exponent. We also addressed tides in this section. It is important to note that the tides are caused by The difference in forces acting on the Earth by the MOON not the sun. There is a bulge around the earth since the tides are caused by the difference in forces. The kinds of tides we have are Spring and neap tides, spring tides occur when the moon and earth and sun are all in a line, this causes higher high tides and lower low tides. A neap tide occurs when the moon is perpendicular to the earth in relation to the sun which causes higher lows and lower highs.

-Momentum/ Impulse + their relationship:
     Momentum is defined as an object's mass times its velocity. In symbols it is shown as p=mv. An object's change in momentum is defined by the equation deltap= pfinal - pinitial. Impulse = force times the change in time. Written as J=f(delta t). Change in momentum = Impulse. Therefore pfinal-pinitial=force(delta t). This is important so that we can solve for a force or momentum given a problem with the right information. A big problem of this unit is a question about airbags and why they keep us safe. We have to explain that no matter how a person is stopped they go from moving to not moving, therefore their change in momentum will be the same. Then we explain that since their change in momentum is the same, so will be their impulse. With an airbag the person decelerates over a longer period of time which means that there is less force on the individual= less injury.

-Conservation of Momentum:
     In this section we learned that momentum is conserved in any collision. This means that momentum before a collision will equal the momentum after a collision. The ways that we can solve problems for if the object stick or don't stick are as follows:
Don't stick- MaVa+MbVb=MaVa+MbVb.
Stick- MaVa+MbVb=Ma+b(Vab).
It is important to know that an individual object's momentum can change without violating the law of conservation of momentum as the momentum of the system is not changed.

What I have found difficult about what we have studied is when we learned about tides and how the tides were in a bulge shape around the Earth. I had a hard time seeing why the bulge on the other side of the earth from the moon was formed.
I overcame this difficulty after Ms. Lawrence explained that it is because of the Difference in forces on the earth that caused the bulges and comparing that to the center of the earth means that one side will have a negative force, meaning it is going in the opposite direction.
My problem solving skills, effort, and learning:
My effort towards class was held constant and high at all times during this unit towards homework and classwork as well as projects and blogs. I tried my best to find understanding when I was confused and have noted the mistakes I have made along the way.
I had a little trouble having patience with problems as some of them were repetitive and I had to resist the urge to say didn't we already do this? I still enjoyed the unit no matter when that question popped up. In my communication with partners I often try to offer what knowledge I may have because I can easily grasp the concepts provided in class, sometimes faster than other students. I enjoy helping others reach understanding of a certain topic and seeing them do well on it in the future.
My goal for the next unit is to not procrastinate and do work at the last minute.
The previous goal I had of asking questions in class was reached in this unit I felt pretty adequately and I will continue on with this goal throughout the year.
I can connect This unit to every day life by seeing car crashes or seeing examples of newton's 3rd law (jumping off a boat) or conservation of momentum (catching a ball and rolling backwards in a rolly chair).

My group's Podcast for this Unit:

Tides resource

This video offers a good visual animation as to how tides are made and how they are affected by various forces. This would be a good video to watch after someone has learned a little bit of basic information about tides.

Unit 2 Blog Reflection

In Unit 2, I learned about Newton's Second Law. This subject includes the concepts of falling through the air, free fall, throwing a ball straight up, falling at an angle, and throwing a ball up at an angle.
    Newton's Second Law is an equation that relates Acceleration, Force, and Mass. This equation is a=fnet/m, which means that Acceleration is proportional to Force, and Inversely proportional to Mass.

      Falling Through The Air:
     When falling through the air, the concept of Air Resistance must be accounted for. Air resistance is the force that air pushes against an object as the object is moving through it. Another key term for falling through the air Terminal Velocity.
     Terminal Velocity is when the force of Air Resistance on an object is equal to the force of gravity on it, therefore the net force on the object is zero. Keep in mind that even though the net force and accelerations are zero, the object is still moving at a constant rate. Two things that increase the force of air resistance are surface area and speed. Supposing you have two objects with the same surface area and different masses, the one with a higher mass will have to reach a higher speed to have the force of air resistance on it equal its weight, therefore this terminal velocity will be higher than that of an object with less weight/mass.
     Terminal Velocity is present when someone is skydiving. When first stepping out of a plane or aircraft, keep in mind that your velocity is 0 m/s as you aren't yet moving, and acceleration is 10m/s^2 because the force of gravity is always present on an object. After one second, your speed will be 10 m/s. After 3 seconds your velocity will be 20 m/s and so on. When solving for fnet, we can use fweight-fair.
     After deploying a parachute, your surface area will be increased, and therefore your net force will become negative. This will give you a negative acceleration, otherwise known as accelerating upward. As we learned before, if an object's acceleration and velocity are in opposite directions the object is slowing down. Even though your acceleration is negative, you are still moving downward at a decreasing rate.
     Free Fall
     Free fall is achieved when gravity is the only force acting on an object and there is no air resistance. When in free fall, we can use the equation d=1/2gt^2 for vertical components of problems as well as v=dt because gravity is the only force acting on it. For the horizontal component of a problem we can use v=d/t, this horizontal velocity will remain constant.
     Throwing a Ball Straight Up:
     When throwing a ball straight up, it is important to remember that we start at the time t=0s. When solving these problems, we must note that we assume the object is in free fall, therefore the only force acting on the object is gravity. Take for example a ball that is thrown straight up with an initial speed of 20 m/s. As the object's acceleration is 10m/s^2 towards the ground, its speed will decrease by 10 m/s every second it is in the air. Knowing this, the object will reach the top of its path in 3 seconds, when its speed= zero. Then it begins its descent which takes the same time that it took to reach the top of its path. We can use the equation d=1/2gt^2 for these problems.
     Falling at an Angle:
     When falling at an angle, we again assume an object is in free fall. The horizontal component of velocity will remain the same throughout the projectile's flight. We can again use d=1/2gt^2 for vertical distance and v=gt for vertical velocity. Gravity will be the only force accelerating the projectile.We can use v=d/ for the vertical component of the projectile.
     Throwing objects at an angle:
     When throwing an object at an angle, we must consider the flight path of the projectile as a parabola. From its highest point (halfway through its flight) we can use d=1/2gt^2 for its height. We must also consider the angle of the throw, as we can use special triangles to help us solve for the actual velocity of the object instead of having to use the Pythagorean theorem a lot.

What I have Found Difficult about what I have studied is finding the height of a thrown object at a certain time during its flight.
I overcame these struggles by reviewing with friends and taking better notes about the subject..
My effort towards the class have been reasonable and I do everything to the best of my ability in the class. Homework is an area that I find i succeed at, as well as quizzes and tests.
I see myself persisting in my efforts in this class and continuing to try my hardest. I think I work well in group settings, trying to contribute ideas to the group as often as I can and trying to be helpful. My self confidence in this class helps my overall self confidence in school and helps motivate me to work hard in all my classes.
Part B:
A connection between what we studied and life that I see every day is the flight of a thrown football. I can relate each and every one of the concepts we learned to what i see on a football field every day.

Free Fall Resource

This is a video I found about free fall. While starting off with general physics concepts, it goes deeper into what free fall actually is and what happens to an object during free fall. It has a nice resemblance to Tom Petty's "Free Falling" song and is thus easier to remember. It couples this songs with easy to see examples and shows how these examples relate with text. I recommend it to people as a starter video for the concept of free fall.

Newton's Second Law Resource

The following video is a good one to watch early in the course of understanding Newton's Second Law. It gives a real world example of how force, mass, and acceleration are all connected, especially how mass is inversely proportional to acceleration.