Unit 3 Blog post

Unit 3 began with the introduction of Newton's 3rd law which states that every action in and action reaction pair has an equal and opposite reaction. Example when you run you push the ground back and the ground pushes you forward. This law is what allows us to move. In a horse carriage the force the horse pushes the ground with is stronger than the force the wheels push the ground with. This push against the ground creates  friction and the wheels have less friction which allows the carriage to move forward. We then moved on to the subject of tides. 

This video is a very good demonstration on how the moon's cycle affects the tides on earth. To get a visual moving cycle helped me understand what exactly happened. This video also differentiates the high and low tide cycles by color. As you can see the high tide starts off as light blue and pulls in as the moon shifts spots, same goes with the dark blue tides. It was very helpful to see the movement of earth's bulge during a 28 day cycle. 

Now this video gives more specifics on how the forces are pulling earth and it's tides. The side of earth directly facing the moon has the largest gravitational force(side 1). The side directly across earth has an equal and opposite force(side 2). Given the equation for the force between two objects F= g(m1xm2)/d^2, side two has less distance between the two objects (earth and moon) meaning there is a larger force. Distance and force are proportional. Side two has an larger distance and a equal and opposite force in the other direction. Say the force between earth and side 1 is 5, the force between earth and side 2 would be -5, a negative force simply means in the opposite direction.  This is why we see equal stretches in bulge from both sides. The earth rotates on an axis so every 6 hours the tides will change from low to high tides. Tides are highest at the new and full moon. These high tides are spring tides the force between earth and the moon are at their greatest. When the moon is half waxed and half wained the tides are still pulled by the moon but are still relatively low. The tides draw from the high tides on the other sides and add to their low tides creating neap tides. Neap tides are always slightly higher than the low tides. It is important to notice that even thought the force of the sun is stronger than the moons that because the greater increase in distance that we mostly feel the moons instead. After learning about tides we moved on to conservation of momentum. Momentum is the change in force over time. impulse is the change in momentum.  In a collision the change of momentum is the final momentum minus the initial momentum. In order to find momentum you must multiply an objects mass by its velocity.  Impulse is measure in Newton's seconds and momentum is measure in kilograms meters per second. To find the exact force at a period in time you take the change in momentum over the specific time. 

Tides

This video is a very good demonstration on how the moon's cycle affects the tides on earth. To get a visual moving cycle helped me understand what exactly happened. This video also differentiates the high and low tide cycles by color. As you can see the high tide starts off as light blue and pulls in as the moon shifts spots, same goes with the dark blue tides. It was very helpful to see the movement of earth's bulge during a 28 day cycle. 

Now this video gives more specifics on how the forces are pulling earth and it's tides. The side of earth directly facing the moon has the largest gravitational force(side 1). The side directly across earth has an equal and opposite force(side 2). Given the equation for the force between two objects F= g(m1xm2)/d^2, side two has less distance between the two objects (earth and moon) meaning there is a larger force. Distance and force are proportional. Side two has an larger distance and a equal and opposite force in the other direction. Say the force between earth and side 1 is 5, the force between earth and side 2 would be -5, a negative force simply means in the opposite direction.  This is why we see equal stretches in bulge from both sides. The earth rotates on an axis so every 6 hours the tides will change from low to high tides. Tides are highest at the new and full moon. These high tides are spring tides the force between earth and the moon are at their greatest. When the moon is half waxed and half wained the tides are still pulled by the moon but are still relatively low. The tides draw from the high tides on the other sides and add to their low tides creating neap tides. Neap tides are always slightly higher than the low tides.
http://tides.mobilegeographics.com/locations/2080.html here is a link to Galveston beach in Houston, Texas. Currently this beach is approaching high tide and will be until 11:45 pm. Currently the moon phase is approaching the last quarter meaning it is about to be in neap tides. 

This video very clearly explains how to find the angle and direction of vectors. The real life example helps this idea stick. Also it is good to get a visual of how to calculate the angle and direction, I feel that I can now apply this to a problem on paper. The reason this video was made was to explain the math behind vectors for beginners like us. This video was not very interesting but clearly and quickly explained the concept which was something I liked. 

Unit 2 blog post

Unit 2 was based off of Newtons 2nd law and how objects move through air. Newtons 2nd law says that acceleration is proportional to force and acceleration is inversely proportional to mass. This can be written out as a=f/m which explains all of Newtons second law in symbols. This law was tested in our cart pulley experiments. To test force being proportional to acceleration (a~f) we put more weight on the pulley(force) and kept the cart weight the same. We noticed that the more force added the faster the cart would accelerate. We tested the second part of Newtons 2nd law by keeping the pulley weight constant but adding more mass to the cart. The more mass added to the cart the slower the acceleration. Through these experiments we confirmed Newtons second law. When learning how objects move through air, we studied skydiving, and variations of free fall. Skydiving is when an object is falling through air accounting air resistance. When falling with air resistance an object will fall much differently than in free fall. Heavier items have more f-weight therefore more f-air resistance. This makes then reach there terminal velocity faster and this is why to a point heavier items fall faster than lighter ones. Terminal velocity is when an object stops acceleration and it's net force reaches zero during the fall. When parachuting a person reaches two terminal velocities. The first one is when they first reach 0 acceleration and net force, their acceleration and net force are downwards. When a person pulls the cord for the parachute the f-weight and f- air become unbalanced, the acceleration is directed upwards and the object begins to slow down. When falling straight down without air resistance only the force of gravity is acting upon you. The force of gravity speed your fall up by 10m/s. So if you are going 50m/s on the 4th second, you will be going 60 m/s on the 5th. When throwing an object straight up the idea is similar except when the object travels up it slows down by the force of gravity by 10m/s until it reaches it's peak in where it is not accelerating at all then it falls and proceeds to accelerate by 10m/s. This video clears up common misconceptions about falling objects in free fall. The man walks around asking people on their thoughts about what would happen if you dropped two equally sized  balls with different weight from the same height. The point of this demonstration was to explain that weight does not change the speed of an object in free fall because the both will have the same acceleration. The only thing that affects the time an object takes to fall in free fall is the height and acceleration of an object. If you were to shot a bullet and drop a bullet shell from the same height, they would hit the ground at the same time because they have the same acceleration and height. This video reconfirmed a topic I struggled with earlier on this unit. It was also interesting to see how my initial thoughts on free fall matched the randomly sampled pedestrians in the videos. What calculates how long the object will stay in the air is the height it reaches or begins at. Any two objects with the same acceleration and height will hit the ground at the same time. When objects are launched at an angle calculate the time will be the same as throwing straight up(twice the time it takes to reach the top). The horizontal velocity will remain the same while the object is in the air. The vertical velocity will decrease by 10m/s each second on the way up to it's peak and increase by 10m/s each second down from the peak. To calculate the horizontal velocity you use v=d/t. To calculate vertical velocity you find the velocity relative to the initial velocity and time the object has been in the air. To calculate actual velocity you create a triangle.  Using the horizontal and vertical velocities as the bases and to find it you solve for the hypotenuse. This calculates the velocity at that second. The same process is doe when calculating speed on falling at an angle. The vertical velocity and height an object reaches determines it's time in the air.

Falling through Air

This video clears up common misconceptions about falling objects in free fall. The man walks around asking people on their thoughts about what would happen if you dropped two equally sized  balls with different weight from the same height. The point of this demonstration was to explain that weight does not change the speed of an object in free fall because the both will have the same acceleration. The only thing that affects the time an object takes to fall in free fall is the height and acceleration of an object. If you were to shot a bullet and drop a bullet shell from the same height, they would hit the ground at the same time because they have the same acceleration and height. This video reconfirmed a topic I struggled with earlier on this unit. It was also interesting to see how my inital thoughts on free fall matched the randomly sampled pedestrians in the videos.

Unit 1 Blog Post

In Unit one of Physics we mostly learned about velocity, speed, acceleration, force and how they compare, contrast and interact. Speed, velocity and acceleration are very similar tops with specific defining details. Speed is simply the distance traveled over a certain time period. Speed however is not classified by direction. Velocity on the other hand is distance over time in a specific direction. Acceleration is the change in distance traveled over time. When accelerating you can expect to cut the travel time short, and the opposite for decelerating. After learning the basics definitions of these terms we challenged to throw them together and answer questions to more in depth understand them. We came to answer like, while having constant velocity you can't have constant acceleration or accelerate at all due to the constant speed and direction you are traveling in. The four equations for acceleration are... 

• V=at 
• d= 0.5(a)(t)^2 
• a=V2-V1/t 
• a= v/t 

In the second equation above "0.5(a)" represents the speed. In class we used ramps to compare the trends of acceleration and velocity. On any given ramp when a ball is traveling down the balls' velocity will always be increasing.  

• In the top left the velocity is increasing, while the acceleration is decreasing
• In the left middle the velocity is increasing and the acceleration is constant
• In the bottom the velocity and acceleration are 0m/s(s^2)
• Middle right the velocity is increasing and the acceleration is increasing as well

These are just some examples of the ways velocity and acceleration interact. When an object is at constant velocity it is at equilibrium meaning all forces around it are equal, but I will get to that later.

Another thing we learned was Newton's first law. Newton's law states that; an object in motion tends to stay in motion unless acting on by a strong enough outer force. Example; When you are in a car moving at a relatively fast speed and come to an abrupt stop you will notice your body jolt forward. This is because your body is in motion while the car is moving and when the car stops your body does not want to stop so you jolt forward until your seatbelt creates enough force to stop you. The second part of Newton'w first law states that; an object at rest tends to stay at rest unless acted on by a strong enough outer force. Example; when leaving coffee on the trunk of a car and quickly driving away you will notice your cup will fall directly below where it was sitting. This is because the cup was at rest and would like to stay at rest so it will fall directly below it's previous location. 

Now back to Equilibrium. When an object is at equilibrium the forces acting upon it add up to a net force of 0. Force is measured in Newtons(N). Example; If Kokayi is pushing a box with 50N of force and I am pushing the box from the other side with 50N of force, the box will have a net force of 0 and will be equilibrium. However, if i raise my force to anything less or more than 50N of force there will be no equilibrium and the net force will be greater than 0. It requires more force to move to objects with higher inertia. Objects with more inertia have more mass. Example a care has more inertia than a chair, so it would take more force to move a car rather than a chair.  

This video should explain everything we currently need to know about inertia and Newton's First Law.

Hovercraft Blog Post

Hovercraft Blog

In class Wednesday we conducted a brief experiment in where we rode hovercrafts. The hovercraft was made up of a wooden shield like piece wrapped in garbage bags tucked in duct tape, and controlled by a leaf blowing causing it to hover. Riding the hover craft felt weird because, the craft viciously vibrated and showed no sign of stoppage.  Most people would expect the hover craft to eventually slow down, however contrary to the common belief because there is no force acting to stop the hover craft it could potentially move forever. With other push based rides such as sledding, skateboarding and roller skating there is no possibility of you moving on forever because you can't reach an equilibrium due to friction. The hover craft taught me that when at equilibrium one can continuously move unless interrupted. When there is no net force it can still be moving it is just maintaining constant velocity. Inertia is just the amount of force to get something to change states of motion. For example Winston took more force to move and stop than Caroline, meaning Winston has more inertia. Accelerating is dependent on the amount of force acting upon an object. Acceleration creates the speed to start and stop in a zero net force situation. Constant velocity is achieved while wondrously hovering from point a to b. In this frame you have no forces acting on or against you.