"What I learned in 1st Semester"

This semester I learned a lot!! The first unit we learned about was Kinematics (1-dimensional and 2-dimensional).  I learned that kinematics is the study of motion.  This is the basics of physics.  After we learned about kinematics, we learned a little bit of graphing that goes deals with kinematics.  The next unit was Forces and Motions. In this unit I learned Newton's 1st, 2nd, and 3rd laws of motion.  I learned that a newton is in units of kg m/s^2 and that weight = mg. Also in this unit we learned about pulleys and because it has one string, that means there is one tension.  Momentum was the next unit we learned about.  I learned taht momentum is a vector that is calculated by multiplying mass times its velocity (units: kg m/s). The law of conservation of momentum is that momentum cannot be created nor destroyed, it can only change forms, so therefore, momentum in equals momentum out.  Similar to this law of conservation, I learned about the law of conservation of energy which basically stated that energy in equals energy out, in the our unit of Work and Energy.  I learned much information this semester and many equations.  All this information and knowledge I learned was written down in my physics notebook so that I will never forget. :)

DO WORK SON!

This week we learned about work and energy.  Work is activity involving effort to achieve a result.  To find work you can multiply the force on the object by its displacement.  The units of energy used is Nm, also known as Joules.  Work = the change in energy.  According the the law of energy, energry cannot be created nor destroyed; it can only change forms (in an isolated system).  The energry of position is an object's potential energy.  You can calculate an object's gravitational potential by multiplying its mass by the gravity by its height.  After learning about work and energy, it reminded me of this weekend.  My mom and I were sitting at the table and she asked me to pass her my pencil case.  I was too lazy to pick it up and hand it to her, so I slid it across the table.  I pushed my pencil case about 1/2 a meter.  If it took a force of 3 N to push the pencil case, the work I would being doing would be 1.5 Joules.  I'm glad I got to learn about Work and Energy this past week, so now I know how to what work and energy is and how it is applied.

Egg Drop Lab...SUCCESS :)

This week we did our Egg Drop Labs! I found this to be a very fun, interesting, and yet kind of challenging experiment to do because Kawai, Lydia, and I weren't 100% sure if our egg was going to survive! We used a 33 cm shoebox as our device.  We glued lots of cotton balls to the inner surrounding walls of the box.  After the box was all cushion-ized, we took a smaller box and glued cotton balls into it. This small box would be the object that held our egg in place.  When we received the egg, we wrapped it in black felt and taped it so that it was secure.  Once we were finished wrapping our egg in felt, we placed it into the small box and closed it.  We then put bubble wrap between the cotton balls on the inside of the bigger box and the bottom of the smaller box. We taped the small box to the shoebox.  We closed the lid of the shoebox and taped it so that it would not fly off during the drop.  If you watch the first video above, it shows how our egg was dropped.  In the second video, you can see that our egg survived the fall!  The reason why our egg survived was mainly due to the cotton balls.  We chose to use cotton balls because we knew that it would absorb the shock of the fall.  I really liked this lab because it was like a mini project and there was a little bit of suspense right before our egg was dropped.  I also liked seeing the various devices that the other groups created.  After all the eggs were dropped I came to realize that this lab wasn't as challenging as we made it to be.  One group had a very simple yet effective device.  They had three sponges.  They cut a whole in the middle of one of the sponges just enough for the egg to fit in.  After placing the egg in the whole, the surrounded the sides with the other two sponges (one on each side).  They then rubber-banded the three sponges together and dropped it! To me, this was the smartest device of them all because it was light in weight and it had LOTS of cushioning which would make the contact time of the sponge and the ground a lot longer than a shoebox would.  But, in the end, I'm just glad our device worked and our egg survived.:)

MOMENTUM!

I finally understand what momentum is and how you can calculate it.  Like I've mentioned in previous posts, momentum is calculated by multiplying the mass of the object times its velocity.  For example, the picture above is of my eraser.  Let's say that this eraser was 2 kg (a very heavy eraser).  If I were to throw the eraser and the velocity it was moving at was 2 m/s, I could then calculate the momentum of this eraser.  The momentum would be 4 kg m/s because I multiplied the mass by its velocity.  We use momentum in our everyday lives.  I am glad I know how to calculate momentum now!  I'm glad I learn something new in Physics everyday :)

More Stuff on Momentum

This week in Physics, we learned more about momentum.  On Wednesday we were suppose to do a lab about collisions to help us learn more about momentum, but I was sick on that day, so I'm not exactly sure how to explain anything about collision.  But, I can explain a little bit about the Law of Conservation of Momentum.  This law states that momentum cannot be created nor destroyed, it only changes forms, momentum in then will equal momentum out.  From this week, I learned the momentum is a vector/  To find momentum you must multiply the mass of an objec by its velocity (P = mv).  The units we use in this equation are kg m/s.  I also learned about impulse and how it contributes to momentum and force.  Impulse is the change in momentum (delta P).  This is then plugged into the equation of force, which equals the change in momentum/change in time (delta P/delta T).  This is what I learned this week in Physics.

My Thoughts on Momentum

Our next chapter we will be covering is momentum.  In order to begin this new unit, Mr. Blake wanted ut to make our blogpost about either what we think momentum is using our own personal knowledge, or doing research on it.  Because I don't really know anything about momentum, I did some research.  I first looked up the definition of momentum and dictionary.com gave me: "the force or speed of movement of an object".  I then looked in our textbooks for more answers.  The first thing in the textbook about momentum was linear momentum.  Linear momentum is defined as the product of the mass and velocity of an object.  The example it gave me basically said that if you catch a fast enough light-weighted ball and compare it to catching a heavy, slow moving ball, then you will move with the same speed.  This helped me to learn a little about momentum.  Before this small research, I only knew how to use the term "momentum" in speaking, but I never really knew what it was.  Now I know something about it!

Friction!

This weekend, I had to move a couple of these big boxes from my living room into the office.  My living room floor is covered in carpet.  The boxes were way to heavy to carry by myself, so I decided to push them.  Although I am not exactly sure what the precise amount of the forces acting upon the boxes was, I do know that the forces that were acting upon it was weight (mg), normal force, the force I used to push the boxes, and also friction.  There was friction because the boxes were on top of the carpet, causing an opposing motion to my force exerted on the boxes.  Many times in the past I have pushed objects across floors, but I never really thought of why it was harder to push things across certain types of surfaces.  I now know that friction is an important part of motion.