Unit 2 Blog Reflection

In unit two we started off learning about Newton’s second law of motion, which states that acceleration is directly proportional to force and inversely proportional to mass. This law can be read as a=f net / mass. With this law it was also necessary to learn that weight = (mass)(gravity). Weight is measured in newtons while mass is measured in kilograms. Next we learned about free fall excluding air resistance. An object in free fall, falls with an acceleration of 9.8 m/s^2. Knowing this, we learned how to calculate how long it is going to take for something to fall simply by knowing the height it falls from or vise versa. For example, when we calculated the height of 3^rd Anderson. After dropping a ball multiple times and taking the average time it took for the ball to reach the ground, we calculated the height. We took our average time and plugged it into the distance equation, d=1/2gt^2 and solved for d. This brought us to the approximate height of 3^rd Anderson. During free fall an object is constantly accelerating at a rate of 9.8m/s^2 until it reaches the ground.

Projectile motion is when something is pushed with a force and is projected through the air. For example, an airplane dropping a box. When an airplane drops a box the box is going to fall at 9.8 m/s^2 vertically, but the horizontal speed is going to remain constant through the reasoning of Newton’s first law. In order to find the vertical distance or time you are going to use the same distance equation that you would use for free fall, d=1/2gt^2. However for the horizontal velocity of an object you are going to use velocity=distance/time. For example, if you wanted to know how far in advance a plane should drop a box in order to reach a certain target you are going to use the formula v=d/t and solve for d.

After learning about projectile motion we learned about objects falling through the air. An object falling through air and an object in free fall are completely different. An object falling through the air is going to increase velocity and accelerate less and less until it reaches a point of constant velocity and zero acceleration. The object is going to reach a constant velocity when the net force of the object is zero. When an object falls, the force of gravity pulls it down according to its weight. The faster the velocity of the object the larger the force of air is going to be on the object. The object falling through the air is going to keep increasing its velocity until the force of air is large enough to subtract to zero when in accordance with the force of weight. An object with a greater weight is going to have to travel faster in order to reach a constant velocity because the force of air is going to need to be greater in order to reach a net force of zero.

Lastly, we learned about throwing things up at an angle. When something is thrown up at an angle you can calculate how much time it spends in the air by using the force of gravity acting on the force exerted on the object. When you find the time, you can calculate how far the object went. Throughout the flight of the object the horizontal velocity is going to stay the same and the vertical acceleration is going to remain at 9.8 m/s^2 at all times, even when the objects vertical velocity is at zero. At the peak of the objects path the velocity is going to be only the horizontal since the vertical velocity is going to be at zero. All calculations pertaining to the vertical velocity or time can be found using the formula d=1/2gt^2. All calculation pertaining to the object horizontal motion can be found with v=d/t.

Falling Through the Air Resource

In this video there is a large amount of people sky diving in formation. You can see that the people control their speed by changing their surface area. When the people broke away from formation you could see that they all made their surface area smaller in order to go somewhere else. This is because the larger your surface area is the slower that you are going to go. It was also clear that when the person taking the video was about to deploy his parachute he reached a terminal velocity and then after he had deployed his parachute his acceleration increased negatively, his velocity decreased, and his net force increased. This all happens because his parachute adds to his surface area making him slow down.

Free Fall Resource

In this video, this man is on a roller coaster ride that will put him in a state of free fall. During this you can clearly see while during free fall, his hair and tie lift up in the air and become weightless while he falls at a rate of 9.8m/s2.

Newton's 2nd law resource

This video clearly describes Newton's second law of motion. Acceleration is directly proportional to force and acceleration is inversely proportional to mass. In this video it is made clear that the ball with more mass went slower and traveled a lesser distance then the ball with the lesser amount of mass when an equal force was applied.

Unit 1 Reflection

In this unit I learned all about Newton’s first law of inertia, which states that an object in motion will stay in motion or an object at rest will stay at rest unless a force is exerted upon it. I learned about net force, which is the total amount of forces acting on an object, equilibrium, which is when the net force on an object is zero. And lastly I learned about velocity, which is a certain speed of an object going in a certain direction, speed, which is how fast an object is going, and acceleration, which is how fast an object is speeding up.

What I have felt was difficult about what we have studied pertains to speed, velocity, and acceleration. It is very simple to get these three concepts mixed up. For example, a car can be traveling at a constant speed with constant acceleration. Or a car can be accelerating in one direction with constant acceleration but not be in constant velocity. Constant velocity requires constant speed, but if something is traveling at a constant speed it may or may not be traveling with a constant velocity.

I overcame these difficulties by completing my homework questions. I had a large amount of homework questions and doing these velocity, speed, and acceleration related questions were very helpful. I have found that I learn very well through repetition so doing the amount of problems that I did and going over them in class and talking about it during class helped me a lot.

Personally, I enjoyed solving the problems that we had for homework. I quickly learned that there were a lot of trick questions. For example, if a car is moving at a constant velocity of 20 km/h for 2 hours what is the cars acceleration? Well there is no acceleration because you are moving at a constant velocity. I got a lot better at reading the question and thinking about what the question is asking for rather then just plugging numbers into equations or restating definitions. Everything required and explanation of reason so that required me to actually think about what I was saying.

My goals for the next unit are to get better quiz grades by showing more steps in my math. A lot of my points got taken off for not showing complete steps in my mathematical equations. The lost points could have been easily avoided if I had shown all of my steps completely.

There are so many connections that physics makes in everyday life. Physics is significant in everything from pushing a box to the importance of headrests and seatbelts. Quite frankly, when I learned how relevant physics was to my life I was shocked. I didn’t know much about physics before I started the class and I am surprised at how much it pertains to my life.

The link to the podcast that I made with Becca and Isabelle on the concept of Inertia is below

http://www.youtube.com/watch?v=0n54MysJW88&feature=youtu.be 

Picture!

In this photo, Megan is hitting a book out from under a water bottle. The water bottle falls straight down rather then flying in the direction that Megan hit the book. This is so because of Newton's first law of Inertia. This law states that an object in moition will stay in motion or an object at rest will stay at rest unless a force is exerted upon it. The water bottle is at rest and wants to stay at rest, so when the book below it is hit, the water bottle stays put until the force of gravity pulls it down.

Trip Problem!

My original answer to the trip problem was 80 km/h. I didn't really use any formula for this answer, i just thought that all of the numbers together looked right. I never took into account the time. With the time as well as the speed, I realized that the car has already been traveling for one hour which would mean that the car would need to go faster then the speed of light in order to meet the average. In order to solve this problem you need to take into account the formula velocity = distance/time. Since I never took into account the time I got this problem wrong, but after discussing this in class the correct answer became clear to me and made perfect sense. 

The next time that I am asked a question similar to this, I will be sure to think about all of the aspects of the question, specifically time.