Horse and buggy/ tug of war

Unit 3 reflection

In Unit 3, I have learned about action and reaction pairs, Newton's 3rd law, how tug of war works, how a horse is able to pull a buggy, adding forces, vectors at angles, gravity and tides, momentum,  impulse and momentum relationship, and the conservation of momentum.

Action and reaction pairs/ Newton's 3rd law

Newtons third law states: every action has an equal and opposite reaction. That means if you touch someone then they touch you back with the same amount of force. In order to find that force you would use the equation:

F=Ma
Reaction and action pairs, are examples of Newton's 3rd law. Here are some examples:

In this picture the man is pushing the wall with 100N so, because of Newton's third law, the wall will push the man back with the same amount of force that the man pushes on the wall.

Another example would be: rocket pushes fuel backward so fuel pushes rocket forward or hammer pushes nail so nail pushes hammer

No matter how hard you push on something it will push back on you with the exact same force. Forces do not exist without other forces.

Tug of war and horse and buggy

How do you win a tug of war contest? It all depends on your firm stance on the ground, because you push ground forward therefore the ground pushes you backward. If you were to wear socks while playing tug of war you would most likely be part of the losing team. This is because if you do not have good traction with the ground you will just slide forward.
How does a horse pull a buggy forward? First it is important to look at the action and reaction pairs, in order to see how the horse is able to pull the buggy forward.

It is important to remember Newton's third law (every action has an equal and opposite reaction). This would mean that the horse and buggy pull on each other with the same amount of force. 

So why does the horse pull the buggy forward? Because the horse pushes on the ground with more force than the buggy pushes on the ground. When looking at the diagram it is important to notice that the arrows that say horse pushes ground back ward therefor the ground pushes the horse forward are longer than the arrows that say the buggy pushes ground forward therefore the ground pushes the buggy backward.

Adding forces and Vectors with angles 

    Vectors are used in order to find things such as the tensions in a rope like the following:

The more tension something (rope) has....the more likely it is to break.

In this diagram the right side would be more likely to break, because there is more tension.

Why does a box slide down a ramp?

Because the gravity pushes it down and the ramp pushes it up, so when the vectors are added together it shows that the box will slide down the ramp.

Gravity and tides 

The universal gravitational force says that, everything with mass attracts al other things with mass. And the formula for this is F=G(m1m2/d^2). 

What does force depend on?

1.) the mass of objects because force is proportional to mass. The small the objects the smaller the force.

2.) the distance between the objects. The force is proportional to 1/d. The greater the distance the weaker the force and the smaller the distance means that the force is more powerful. 

Is the force of gravity greater at high elevations or at sea level? 

It is greater at sea level, because the distance would be much smaller at the beach then say at Mt. Everest. This is because it is measured from the center of the earth which is closer to sea level than Mt. Everest is. 

      Why are there high tides on both sides of the earth? Why not just the side closest to the moon, because the force is greater with the smaller amount of distance? 

      Because when the earth pulls on the moon, the moon pulls back on the earth so that is why there is a high tide on the opposite side of the earth. 

       When the sun, moon, and the earth are all in line we experience Spring tides. (full/ new moon) This means that the tides are higher than they normally are.

        When we experience a half moon then the tides are called neap tides. This means that the tides are lower than they normally are. 

        Although the sun has a stronger force on the earth than the moon (because it has a greater mass), the difference between the moon and the earth and the sun and the earth is smaller, so it has a stronger force on the earth thus the distance is what causes tides.

Momentum/ Impulse and momentum relationship

     The proper way to answer a question regarding Momentum and Impulse, is:

     Why do climbers prefer stretchy ropes to non-stretchy ropes?

            -Because no matter how the climber is stopped, the climber goes from moving to not moving, therefore the change in momentum is the same no matter how the climber is stopped.

           -p=mv

           -p= pfinal-pinitial 

- Since the change in momentum is the same no matter how the climber is stopped, the impulse will also be the same

-J=p

 

---------------> the more time= the less force

       -The climber prefers a stretchy rope rather than a non-stretchy rope, because it increases the time it                  takes for the climber to come to a stop, thus because the impulse is constant the force will be less. A smaller force means the less injury when the climber comes to a stop. 

Conservation of momentum

     The conservation of momentum means that the momentum before, after, and during the collision is the same no matter what. This means that if a car and a truck collide head on the momentum of the system will always be the same. The momentum of the singular car though can have a change in momentum, just not the whole collision. 

Here is an example:

Cart A and Cart B are moving in opposite directions and they stick together after they collide.

How fast will the carts be moving after the collision and in which direction will the carts be traveling?

      

Conclusion

      The most difficult part of this unit for me was understanding vectors as well as the momentum and impulse relationship. I feel like this blog post has helped me to review those concepts so reviewing my notes and having to explain these things really helped me. Another thing that has helped me is watching the podcasts made by my classmates, as well as making one with my group. 

      I would say that I have put a lot of effort into the class and I really enjoy to structure of the class. I have completed almost every homework assignment and have come in during conference period if I didn't understand something. I also feel that working in small groups has helped me grow in this class. It is nice to be able to discuss certain concepts that I struggle with and ask questions. 

       

Tides resource

This video provides a very clear and engaging explanation of tides and how the moon and the sun have to do with it. The creator of this video made a diagram of where the moon has to be when there is a high tide and low tide. The side closest to the moon will experience high tide because of the gravitational pull and the opposite side will experience the high tide as well because the earth is pulling on the moon as well as the moon is pulling on the earth. I definitely believe that this video helped me to see how the tides are effected by the moon. When the moon is full then the tides will be higher than normal and when it is a half moon the tides are lower than normal.

Unit 2 Reflection

Newton's Second Law:

Newton's Second law states that acceleration is directly proportional to force and inversely proportional to mass, or a=F/m. Whenever mass increases, the acceleration. When looking at mass vs. weight, weight=(mass)(gravity), or w=mg. and example equation of this is:

Skydiving:

Skydiving is an example of Newton's second law in action. Here is a diagram of what happens when you leave the plane:

In the last part of the picture, the skydiver is in terminal velocity which means they are going as fast as they possibly can but are no longer accelerating. After they reach terminal velocity they parachute goes up. Once the parachute comes out, the surface area increases as well as the net force. The velocity continues in the downward direction, but now the acceleration is in the upward direction. This means that the skydiver is slowing down. Then the skydiver hits terminal velocity again where the F air is the same as before but the skydiver is moving slower, because of the parachute. They are no longer accelerating, but are moving in the downward direction.

Free Fall:

Free fall is when an object falls, with no air resistance. An example of this that was shown in class is a penny and a feather were placed in a tube with no air in it. When the tube was flipped over, the penny and the feather hit the ground at the same time. The only force acting on a object in free fall is the force of gravity. The equation used to determine the acceleration in free fall is : a=fnet/m. When you are searching for the distance, you use the equation: d=1/2dg^2. And when you want to know the velocity the equation v=gt is used. 

Projectile Motion (falling at an angle):

Projectile motion is when something is thrown or dropped. An example is when you drop two balls on the ground. If you were to shoot a ball off a table and drop a ball of the same table at the same time, they would hit the ground at the same time. The only thing that matters is the height. The balls hit the ground at the same time, because they left from the same height. When a person jumps off a cliff you must know the vertical and horizontal distances, speed, and time. When determining horizontal you use the equation: v=d/t. When determining the vertical you use: v=gt or d=1/2gt^2. When you hit the ground, you realize that you took a curved path, because you are moving both vertically and horizontally. 

Free Fall (falling straight down):

Free fall is when something falls and the only force acting on it is the force of gravity. The main thing to know about free fall is that there is NO air resistance. The weight of the object falling in free fall does not matter, because the only force acting is the force of gravity. If you were trying to figure out how high a cliff is and the only information is that an object falls off of it and falls for 9 seconds. You would use the equation d=1/2gt^2. 

Free fall (throwing things straight up):

When you throw an object straight up, neglecting air resistance, the object stops at the top of it's path and falls back down. The balls acceleration remains constant the whole time. The acceleration is 10 m/s^2, even when the ball's velocity is 0 m/s at the top of it's path. If the ball starts off at 40 m/s then the next second will be 30 m/s and the velocity will continue to go down until it is at the top of it's path and then it will accelerate back down at 10 m/s^2. 

Free Fall Resource

In this video, a man explains exactly what free fall is. He preforms a demonstration with a heavy ball and a light ball. He drops the two balls and they hit the table at the same time. He then goes on to explain why this happens. The reason the balls hit the table at the same time is because they have the same acceleration.

Newton's 2nd Law Resource

This video was really helpful in understanding exactly what Newton means in his 2nd law. The demonstration of the balls being shot out of 2 tubes helped me see that an object with less mass will move quicker than an object with more mass. This video helped me see Newton's 2nd law in a real life scenario.

Net force and Equilibrium Podcast

Blog Reflection

     In this unit I learned about Newton's First Law, Inertia, Net Force, Equilibrium, Speed, Velocity, equation for a straight line, and Acceleration. I also learned different formulas and equations to go along with each of these concepts.

     

Newton's First Law and Inertia: At the beginning of this unit, the first things we talked about was Newton's First Law and Inertia. Newton's First law states that an object at rest tends to stay at rest unless acted upon by an outside force, and an object in motion tends to stay in motion unless acted upon by an outside force. Inertia is another way to refer to Newton's First Law. An example of Inertia is when there are plates on top of a table cloth and someone pulls the table cloth out from under the dishes and the dishes remain on the table. They remain at rest and don't move with the table cloth, because they were not being acted upon by an outside force. Inertia is occurring but you cannot say that the reason this happens if because of Inertia, because Inertia is a property. Another good way to think of Inertia is by saying things like to continue doing what they are doing, so if an object is at rest it will want to stay at rest. One more example of Inertia is if you throw a penny up in your hand it will land right back in your hand. There is no force that is causing the penny to move forward with the car.

   

 Net force and Equilibrium: Netforce is once or more forces acting upon an object at once. A force is either a push or it is a pull. So and example of net force would be the following:

This is an example of an object moving at a newt force of 10 newtons. Newtons is the measure of force. If the force of friction ( the amount of resistance) were to be 10N then the net force would be equal to 0N which would mean the object would be at equilibrium. If an object is either moving at a constant velocity or the object is at rest then it is at equilibrium because there is no force, or the force is equal. 

       

Speed and Velocity: Speed is how fast an object is moving. There are many ways to measure speed but in Physics the most common way is m/s. In order to determine speed, you have to use the equation which is distance/time.  Speed is different from velocity, because velocity requires a specific direction. Velocity is the speed of an object that is moving in a specific direction. In order to change velocity, there needs to be an outside force acting on the object. Another way to change your velocity is by changing direction. Changing direction does not change the speed though. An example of this is a race car rounding the corner at 90 km/hr. The car would continue at a constant speed but it would not be going at a constant velocity, because it is changing direction. 

Equation of a straight line: The Equation of a straight line is y=mx+b. The y in this equation stands for time and the m stands for 1/2 a and the x stands for time^2. So this equation could also be written as d= 1/2 at^2. 

     

 Acceleration:  Acceleration means an increase or decrease in speed. In order to find acceleration you would use the equation of change in velocity/ time. The unit used for acceleration is m/s2. 

 In this picture, it shows how the ball accelerates based on the height of the ramp. If you want to determine how fast an object is moving then you would use v=a (acceleration) x t (time). And if you want to figure out how far an object is going you would use the equation d=1/2 at2. Acceleration means how much the object is speeding up. In order to have a constant acceleration then the increase must be equal. For example going from 52 to 54 to 56 would be a constant acceleration, or going from 56 to 54 to 52. If an object is moving from 50 to 58 to 59 then it would not be constant. 

      Me as a Student  

       I think that the the most difficult part for me this unit was the equation for a line and graphing. After watching the video made by my classmates about graphing and equations, it made it much more clear. I took notes on that video and I understand when and why I use certain equations. I also reviewed labs and old notes to see where I used this equation. The lightbulb clicked for me when I re-watched the podcast on this topic, because they explained it in a way that made it easy for me to understand. They also had visuals which made it even clearer.

      I think that I have had a pretty good understanding of Physics so far this year. I have completed my homework, and I really appreciate the videos Ms. Lawrence made because they helped to hammer in the concept that we learned. I think that the blogs have been successful in helping us as students explain what we have learned. I think that I have put a lot of effort into making sure my blog posts are good, but I do think that there is room for improvement. One way I could improve my blog posts is by making them even more detailed and accurate. In Physics I see the use of creativity by coming up with scenerios that Physics can be applied to such as a car driving around a race track. I think that I do take my time working on problems, but I could be even more detailed in my answering. My goals for the next unit is to make sure I completely understand a concept before taking a quiz on it. I also need to work on showing all of my work on a quiz. I could do this by writing out the formulas and all the information needed on a problem even if it seems unecessary before completing it. I think that I also need to participate and ask more questions in class. 

Making Connections

      

    Physics is seen in everyday life. A few examples of where is see Physics include driving down the road and in sports. When I drive to school and we turn out of my driveway onto cane creek road, we are experiencing a change in acceleration because we are both turning and speeding up. We are not moving at a constant velocity though when we are moving, because we are changing speed and direction. During field hockey practice I see Physics all the time. When I hit the ball it is not longer at rest because I hit it with an outside force. The stick causes the ball to move until the grass (another force) causes it to slow down and eventually stop. If the ground was completely flat and even then the ball would continue to move because an object in motion tends to stay in motion unless acted upon by an outside force. 

Constant Velocity Vs. Constant Acceleration

     The purpose of this lab we just finished was to deepen our understanding of the difference between velocity and acceleration and to learn how to solve for how fast and how far something is going using the equation of a line. We also learned how to translate the equation of a line into words then numbers.
During the lab it became clearer the difference between constant velocity and constant acceleration.Constant velocity means that the object is moving at a constant speed. There is no acceleration or change in speed. Constant acceleration means that the object is speeding up or slowing down at a constant speed.
    In the lab we rolled a marble down a flat surface to determine the constant velocity, we did this by making a mark of where the ball was every second and then measuring the distance between the marks using cm. We did the same thing to find the acceleration of the marble but it was on a ramp instead so the marble was constantly speeding up.
    I learned that if something is moving at a constant velocity, it cannot be moving at a constant acceleration because that would mean constantly speeding up and in order to have a constant velocity it needs to be at equilibrium. The formula that is used to determine constant acceleration is a= the change in V/ time. The equation for constant velocity is v=distance/time. Another distinction between constant velocity and constant acceleration is the line graphs. A line graph for constant velocity would be a straight diagonal line whereas a line graph for constant acceleration would be a curved line that becomes steeper as it accelerates. The line graph and the line equation support my data because it shows how constant velocity has an even distance between every mark (second) and for acceleration the graph shows how the ball sped up and covered more distance in less time.
    One important thing that I learned from this lab is how to take a line equation and translate it into words such as distance and time. I am sure that I will see this equation much more throughout Physics class this year. This lab also helped me with the other equations we have learned such as the equation for how fast and how far something is going. Another thing that became more clear is how to determine whether something is at constant velocity or if it is moving at constant acceleration. This became much more clear to me when we did the experiment with the marble on the table. One other thing I learned is how to graph my results and figure out the equation of the line.
 
   

Velocity and Acceleration Video

This video helps to further explain exactly what acceleration,velocity, and speed is and how they are different. There are examples given such as using runners to figure out who is faster. It helped me to understand the different equations and how acceleration, velocity, and speed are different. Another example is of a car traveling from one town to another and using the equation of d/t. Having a constant acceleration means that the object is speeding up at a consistent rate, and having constant velocity would mean the same speed. This video helped me to further my understanding of these three concepts.

Hovercraft Inertia Lab

A.) Unfortunately I wasn't able to ride the hovercraft because it broke, but I hear from my colleagues that it was smooth and it kept a constant speed. I also hear from them that it took a lot of force to stop because it was moving at a fast speed. Riding a hovercraft is different from riding a skateboard or sled, because both a sled and a skateboard have contact with the ground where they experience friction. You feel the bumps and other obstacles which cause the skateboard or sled to slow down and stop if a force doesn't push the object forward.

B.) I learned how the object moving with keep a constant velocity and it won't even slow down unless an outside force acts upon it. I also learned that to have a net force of zero the two forces pushing the object must be using the exact same amount of force. In this lab I also learned exactly what equilibrium is. It means that all forces are acting at a single moment, which I saw in phase one and three of the hovercraft lab.

C.) Based on this lab, acceleration depends on the person's mass riding the hovercraft as well as the net force. The mass is important in acceleration because the smaller the person the faster the acceleration and the bigger the person the slower the acceleration. The net force is important in the acceleration because if one of the forces is pushing the hovercraft with more force then it will accelerate but if the two forces are equal then there will be no acceleration.

D.) Based on this lab you would have constant velocity when you are pushed. You will remain at a constant velocity until there is some sort of outside force that acts on the hovercraft.

E.) Some members riding the hovercraft were harder to stop on the hovercraft either because they weighed more, or because they were moving at a faster speed.

Inertia Demonstration

In this video there are two eggs that are being spun. One of the eggs is raw and the other is hardboiled. The hardboiled egg spins easily and smoothly while the raw egg is more bumpy because of the yolk inside. When the raw egg is touched while spinning it continues to spin, whereas the hardboiled egg stops completely. The raw egg continues to spin because the yolk inside never stopped moving or had any outside force acting upon it. This is a clear demonstration of inertia and Newton's first law which states an object in motion tends to stay in motion unless acted upon by and outside force. Although the egg was acted upon by and outside force, the yolk inside was not. The yolk caused the egg to continue spinning because of inertia. This video was helpful to understand this concept because it shows in a simple way how an object will continue moving unless it is directly acted upon by an outside force. This video made this concept helped me to understand that there could be an object inside of another object that causes it to keep moving.

Physics This Year

       This year in Physics I expect to learn about how and why things move, such as why one object when dropped might hit the ground faster than a different object that is dropped at the same height. Another thing I hope to learn in class this year is how certain safety regulations are made and how they work. I am also very interested in understanding ocean tides and how and why waves form and crash on the beach. I that by the end of the year I will be able to see Physics in life outside of the classroom.
       Physics is an important subject to know for many people because Physics is seen in everyday life. It is an interesting way of understanding how the universe works and it explains why things are the way they are. Without studying Physics, we wouldn't have computers or be able to understand our environment so I think Physics is very important to learn.
      One question I have about Physics is how it relates to sound and sight. One other question I have about Physics is how it was used to build computers and how Physics is related to calculators and how they answer such tedious questions. Lastly I would like to know other ways Physics is seen in everyday life such as in a action movies or in a soccer game.
      One goal that I have this year in Physics is to always go to Mrs. Lawrence or my classmates for help whenever I need it. Along with asking for help I don't ever want to get behind because I don't fully understand something. I also want to make sure I stay focused and attentive during class discussions and projects. My last goal is to always do a thorough job on my homework, and not turn in one late assignment.