Torque

I did not have a working camera this weekend, so i compiled a bunch of pictures i found in my iphoto album that i could identify torque in.  I found this picture of when i went to the seattle space needle this summer.  When i looked through the telescope thing, it was at rest and no torque because there was no rotation.  When i turned it toward the camera, i realized there was torque because i was pushing with my right hand perpendicular to the lever which was from my hand to the center of rotation where the telescope was rotating.  

The picture with Kenji shooting away on the anti-aircraft artillery is similar to the telescope picture.  Although her is applying force to the lever, there is no torque because his force is perpendicular to the lever.  When he turns the gun to shoot the imaginary planes, there is torque because his force is now perpendicular as he applies force from either the left or the right using his left and right hands.  The lever is from his hands to the axle on which the gun is rotating.

Behind the counter of this lovely cabin in the mountains of Washington's Olympic Peninsula, my Aunty is cutting zucchini.  There is torque in her cutting motion as she keeps the tip of the knife on the board and lifts only the back up continuously slicing down on the vegetable.  She applies force with her hand down on the handle.  The handle is the lever from the hand to the tip of the knife which is the center of rotation.  The torque increases as she holds the knife farther from the center of rotation making the zucchini easier to cut.

Sticky Collisions

I just realized that whenever I catch a wave i am demonstrating physics.  When i am floating on the water, i am, for the most part, a stationary object.  My velocity is zero meters per second.  The wave approaching me is traveling at a certain velocity and if this is an example of a sticky collision, it has a mass too.  After I catch the wave, i have the same velocity as the wave, assuming i am riding the wave straight forward.  To find the final velocity of the wave and i the equation for a sticky collision is mass of the wave times the velocity of the wave plus the mass of me times my velocity equals my mass plus the waves mass, times the final velocity.  In a sticky collision, the my momentum before i caught the wave plus the momentum of the wave is conserved and equals the same momentum of me and the wave after the collision. I am sure a wave is not a good example since it probably does not slow down when it collides with me as it is related to the wind and tide and would have an ambiguous mass, but it reminded me of the concept of sticky collisions.

Physics on a hill

This Sunday, justin was riding erin's bike around her neighborhood exploring the different streets of kapahulu.  He had already gone down the other end of the street, but was reluctant to climb the mountain at the other end a little afraid he couldn't handle it without walking the bike up the hill.  He remembered he was a man and could do anything so he contemplated whether it would be easier to go straight up or to gradually zig-zag up the hill.  Because of physics class, i already knew the answer, but said nothing when justin said he would find out which technique would require less work.  As a result, he experimented and went up twice both ways.  The first time he went up the hill somewhat quickly, but looked quite winded at the top and took him a while to come back down as he caught his breath.  As he neared the top of the hill, he could feel the potential energy building as it got harder and harder to peddle.  When he rolled down the hill i noticed his kinetic energy was building and potential energy was decreasing.  The second time he zig-zagged up and it seemed to be a lot easier and less strenuous, although it took him forever to get up.  He realized, if he used more energy to get up the hill, he took less time, but when he put in less energy, he took longer to get up the hill.   So justin learned today that either way he went up the hill he put in the same amount of work.

This battleship represents my brain in physics.  With a little maintenance and guidance I will sail smoothly through the chapters.  Physics for me is  a lot easier so far than bio or chem was for me.  Bio was interesting, but my teacher didn't really teach me anything very well.  Chemistry was just ridiculous because we were learning about things we can't even see so i never understood the big picture.  Physics seems more comprehendible to my brain because i can actually imagine what is happening.  It is not like other sciences where you're assuming these things are occurring between two objects even though you can't see them.  In physics, you can picture what is going on in the questions.  Although It is easier for  my brain to relate to, it does need a lot of steering in the  right direction to get back on course.  Once i am in the right direction and know what i am doing then i understand it and don't really forget.  But when starting new chapters, i am usually pretty lost like navigating in that battleship through uncharted areas.  I have a hard time doing the homework.  Homework and sometimes labs take me a long time to complete.  That's is when i need the help cause i am sailing in untraveled areas. haha.  I think i can do better is i do more practice problems before tests because the questions are all about figuring out what the question is asking and remembering how to do them.  My goal is to be able to see anything throughout my day and understand the physics of it.

Broken Bracelet

  

Yesterday, I was cleaning out my room when I found a bracelet from when I was little.  I was very excited because it used to be my favorite bracelet with the smooth beads until I lost it and never saw it again, 'til now.  I was walking to the kitchen and slipping it on my wrist when the worn string holding the beads together disintegrated and all the beads cascaded toward the cork floor.  The beads went in all directions.  Some went onto towards the kitchen table, others went under the couch behind me, and some hit the wall.  I noticed as the beads of my favorite bracelet from my early childhood days spread throughout every direction of my floor that there was some good after all.  Even though it was the last of that bracelet, until I put the beads on a new string, I noticed some physics.   I noticed the beads on the cork floor stopped quite shortly after they hit the floor and the bead that reached the smooth tile farther away went even further.  FRICTION!  The smoother white tile had a lot less friction than the cork tile.  The friction from the cork tile caused the beads to slow to a stop shortly after they landed making my clean up easier.   The one bead that fell closer to the white tile went further once it reached the smooth surface because there was less friction making it difficult for me to track it down.  I also noticed that my beads were demonstrating Newton's first law, an object remains at rest or maintains a constant velocity unless a net external force acts upon it.  The beads were at rest on my bracelet until the string broke and the upward or normal force of the bracelet string and my arm were no longer acting on the beads and the downward force of gravity was the only force acting on the beads which no longer had a net force of zero.  Even though my fav bracelet is no longer, at least I got to watch and analyze everyday physics.

Saving the Earth Can Be Fun

This picture shows Gavin making a game out of saving the Earth.  He just ran out of his stick of chapstick and knew he should throw it away.  I caught him just as he was shooting it into the rubbish net. The empty chapstick container is a perfect example of a projectile.  A projectile is anything dropped, shot, struck, or thrown under the influence of gravity where air resistance is nonexistant or negligable.  A projectile's velocity can be separated into two parts, horizontal and vertical.  Throughout the path of the chapstick container, its horizontal velocity does not change.  Although the horizontal velocity remains constant, the vertical velocity of the chapstick container changes until it hits the base of the rubbish can, assuming its path is not obstructed by any other object.  The vertical velocity of the chapstick is completely independent of the horizontal velocity and the other way around.  If Gavin were to shoot the chapstick again with less force, missing the shot, the chapstick would hit the floor at the same time as it hits the bottom of the rubbish can.

Physics on my Bike

Today is a lovely day for biking.  I road around my neighborhood on my bike until I came to the end of the road.  I decided to turn left around the corner and ride down another street.  I approached the turn with negative acceleration even though I was moving forward because my rate of change in velocity was increasing as I slowed down.  As I was turning, I was still accelerating even though I was moving at a constant speed because I was changing directions.  Acceleration is change in velocity over change in time.  My change in direction was changing my velocity because velocity is displacement over elapsed time.  As a result, I was still accelerating as was rounding the corner.  After I turned  with constant speed and positive acceleration, my acceleration increased as I sped up out of the turn in a forward direction.  After I circled around the block I had a negative acceleration coming to a stop in front of my house.  My acceleration was negative because my change in rate velocity was decreasing as I came to a stop.  Whenever I ride my bike I will always remember the day I realized I was accelerating as I turned down that street today.