Application: Glogster

Kinetic friction is when an object is in motion while static is while the object is stationary.  Using Newton's first law to find out why static friction is more than kinetic friction check out my glogster, click here!

Reflection Circular Motion and Gravitation

From this unit I have learned many things, I have learned new equations, I have come to better understand how/why objects move and have come to understand forces better. One of the first things we learned about were periods, these are a little tricky but help greatly in the problem solving procedure. They help with finding the velocity, in the beginning of the problem you are given how many rotations a minute or a second an object makes. You would then convert this to Hertz and then to seconds.

I have also learned about how objects move in circles. For example when an object is moving in a circular motion the velocity vector is tangential because it is always changing direction. The objects accelerations is always directed toward the center of the circle. So therefore in circular motion and objects acceleration is always perpendicular to it's velocity.

 I have also learned what keeps the objects moving in a circle. To keep the object moving a centripetal force must be applied, this is not one specific force but rather could be any, i.e. friction of gravity. When objects move in vertical circles the centripetal force is different. Usually at the highest point of rotation the object centripetal force is equal to the force keeping the object in the circle plus the gravitational force then set equal to the mass times the velocity squared over the radius. At the lowest point the equation is the same but you subtract the gravitational force. But that is not always the case, depending on the way the forces are going you could have two equations for subtraction.

In some problems the forces are in different places. Problems that have to due carnival rides often have their forces in very different places, but still spin in a vertical motion. In these problems the firiction force can be in the upper y-axis and the normal force in the x-axis. Because of where the forces are you wouldn't necessarily solve the problem with the equations I stated above. You might do a sum of the forces in the y-axis or use the centripetal force equation. Overall there is no equation set in stone that you use to solve vertical circle problems. You have to evaluate your problem, draw an FBD, and choose that best method/equation to solve for with the facts you know. To sum it up the equations motions of vertical circles is different then horizontal ones.

I have also learned about universal gravitation. " Every object in the universe attracts every other object in the universe with a force that varies directly with the product of their masses and inversely with the square of the distance between the centers of the two masses" or the Law of Universal Gravitation sums it up perfectly. With this. This helps me figure out the what the gravitational pull between two object is or their masses or the distance between the two.I have also learned to find the acceleration due to gravity with any object.

This unit has been one of the most challenging for me. I have had to learn many new equations and how to use/when to use them. I have also have had to be very carefully with my fingers since I have been calculating big, long numbers. Again slowing down and reading the problem completely have lead to some mistakes in my work. I have also learned to make time in my day to review my notes even when there is not a test or quiz.

Gravitational problems have been hard for me because of the big numbers and to solve it is not also plug in the numbers but I have to go through steps or think about how to solve, that it is not just the given equation at the beginning of the notes.With this unit my finger skills have become much better. When I do not get a problem correct I check to make sure I have calculated correctly first.

My study habits have become better, with studying not just when needed. But as always my need to slow down and really read the problem has come into play. Also making sure I really understand the material and am not just solving the problem to finish it. I still need to work on things like slowing down, reviewing , and being careful in my work but I'm getting better with all of these things.

Newton's Second Law

Newton's Second Law has been the toughest for me to understand out of the three laws. Newton’s Second Law helps us understand moving bodies by linking the cause and the effect (or force and acceleration) in a definite way. In the definition of Newton's Second Law it states that acceleration of an object is proportional to the net force and inversely proportional to the mass of an object. I found that very confusing until I learned the equations a=ΣF/m and ΣF=ma. These equations are the key to understand Newton's Second Law.  The equations and FBDs helped me solve problems that involved gravity, tension and applied force. After mastering the equations I came to understand how things are inversely proportional to each other.  For me though it was not just knowing when which equation or knowing what forces to use, but understanding why I would use each force/equation in a problem. This I think helped me get a better understanding of the second law. I may understand Newton's Second Law now, but I did have trouble mastering it. I have found a number of things difficult about the second law. One thing that I found hard was the direction the object was moving. If an object is moving upward the tension force (the force is usually tension) comes first in the equation. But when the object is moving downward the gravitational force comes first. In the beginning I did not understand this; I thought one force comes first no matter what. But after I came to understand that the direction the object is going affects the order the forces in the equation this problem was fixed. Another thing I had a bit of trouble with was inclined plans, I again had to refresh myself on SOH CAH TOA, but after that angles and inclined plans were a breeze. Just because I have survived this class for 1/2 a year does not mean I go without mistakes, my problem solving skills are stronger but not bullet proof (yet). I again have to remind myself to SLOW down. I have tendencies to rush through the problems as fast as I can. But I have gotten much better at slowing down reading the problem, thinking what I know, and using that information to solve. FBD's have been another small problem for me, in some problems I neglected to draw one. Since making many errors I have learned to make and FBD for every problem, even if not required to help. The making of an FBD helps show me how to set up my equation the right way. 

Newton's First Law

I learned many things from our studies of Newton's first law like FBDs, translational equilibrium, inertia, how to find the sum of the forces, or find the value of one specific force. I had heard of Newton's First Law before studying , but I hadn't really known what it was. The law basically states that objects at rest stay at rest and objects in motion stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This goes along with the idea of inertia and how objects resist change in motion. An object has forces acting upon it keeping it in motion, slowing it down, or keeping it from moving. To show all the forces acting on the object we learned to make FBDs or Free Body Diagram. These helped me get a clear visual of the forces acting on an object and would later help me when I was finding the sum of the forces or the value of a force. To find the sum or value of forces, you have to know about translational equilibrium or when the vector sum of the forces acting upon an object are equal to zero. To find the sum or value you would add or subtract(depending of the axis) the force and set them equal to zero. We would apply SOH CAH TOA to adding or subtracting the forces. We would use a separate equation for each axis.
The most difficult thing for me in this unit was finding the angle, when one was not given. In some of the problems especially the ones where the axes had to be tilted I had trouble finding the correct angle. I learned to add horizontal and vertical lines to the drawing and  to make a right triangle with each of the angles and find the sum of the last angle. I then could apply the angle found the the correct equation and solve. I have learned many problem solving skills from this unit the main one for me was patience. While doing the homework and classwork I learned that you can't just go through the problems fast and carelessly. I had to start from the beginning and draw the correct FBD with all the right forces then figure out what I was trying to solve for and if needed find the correct angle. Then make an equation that would solve the problem. I also had to remember all of the trigonometry that I had learned in the first trimester; going back to those pages to look at the things I had forgotten like when to use SIN and When to use COS. Also to solve an equation that I had to make. I had to get used to the idea that I would not just plug numbers into an equation and calculate that I had to make one myself and then solve. This unit also had me go back and carefully check my work because if I started off wrong from the beginning it would mess my whole problem up.

There are many ways Newton's First Law is used in our everyday world. For example pulling my heavy backpack across the floor, I'm applying a force. Or when a car is braking the friction between the ground and the tires. Or when they are building bridges and they have to figure out at what angles and the the weight the bridge can be at to have it be safe. Or when you are hanging object on your Christmas tree, you have to have a strong branch to support the heavier ornaments. Also when you roll a ball it doesn't stop until friction or it hits something.

Content-Acceleration

Dear Grandma,
I got your letter and I would love to answer your questions about acceleration, to help you better understand your knowledge of physics.
Well the direct definition of acceleration is the the change of velocity over a period of time.
Q1) Is acceleration just when an object is speeding up?
No. Acceleration is just the change in velocity, whether that object is speeding up or slowing down it does not matter.
Q2) When does acceleration happen?
Well as stated above it happens when and objects velocity changes. Acceleration also happens when the object changes direction. For example if a car is turning. Acceleration is a vector quanity, so that means it invloves both magnitude and direction. The speed of the car stays the same, but the direction the object is moving changes.
Q3) What is free fall and how does it relate to acceleration?
Gravity is a force and when an object is in free fall and air resitence can be neglected, the acceleration due to gravity is 9.8m/s^2
Q4) Why is acceleration a vector quantity?
Vectors include both magnitude and direction. Acceleration depends on what direction the object is traveling in(either positive and negative) and the numerical value.
I hope I have answered all of your physics questions clearly, please write me if you have any more.

With Love,
 Emily

Content-Acceleration

My Glogser on Acceleration!

Content-Acceleration

Acceleration Wordle: