Power/Work/Force

This week in physics we learned about force, power, and work. We learned that work is equal to force multiplied by distance. So W = fd. This means that the farther you go, the more work you do. Force is equal to mass*acceleration. Then there is power. Power is equal to work divided by time.
These are all related in some ways.  In the picture above, you can see the route the receiver ran. If his acceleration was 2m/a and he has a mass of 89kg then his force, 98kg(2m/s) is 196N. Now that we have the force we can find the work. Work is just force(distance). If the receiver ran 25m then the work would be  w= 196(25) = 4,900 J.  Now with the work we can find power with work divided by time. So it could be 4,900/4 which is 1,225 W. And that's how we find power

What I Am Thankful For In Physics

So far this year in physics we learned about things like momentum, motion, and vectors.  But the thing I am most thankful for is Newton's first law.  An object in motion tends to stay in motion unless acted upon by an unbalanced outside force.  The reason why I like this is because it can apply to sports.  For example in baseball and football when the ball is hit by either a football or by a bat, force is applied to it causing it to accelerate.   If there wasn't an unbalanced and outside force called gravity the ball would keep flying and flying.  But because of gravity the ball falls.

Momentum

     One thing we learned this week was momentum and how it works.  Momentum can be defined in different ways however they are fairly similar.  One definition I have is: Momentum is the speed or force of forward movement.  An example of this in real life is when on car gets into an accident with another.  A lot of times, accidents occur in parking lots or when people aren't paying attention at a stop light.  When one moving car hits another non-moving car, the momentum from one car is transferred into the other car.  To determine the amount of momentum, we use a simple formula, p=mv where p is momentum, m is mass, and v is velocity.

Forces That Accelerate

     When ever there is a force placed upon something, it will accelerate.  If it accelerates, inertia will  make it keep accelerating, or more specifically, it will have it remain unchanged.

An example of this is a baseball and a bat.  When a baseball is flying through the air, it would keep going and going if it was not for the unbalanced and outside force known as gravity.  However, when it is hit by a bat, the force of the bat will cause it to accelerate.  We can find out the force that was put on the ball by a simple equation.  Fnet=ma where m=mass and a=acceleration.

Newton's First Law

     Newton's first law states that an object in motion/at rest will stay in motion/at rest unless acted upon by an outside, unbalanced force.  This means that without an outside unbalanced force, moving objects would keep moving.  It would go and go.  So what makes things stop?

     In the video above, a ball is seen rolling toward a wall.  According to Newton's first law, this ball is to stay in motion, unless an outside unbalanced force affects it.  The ball rolls toward the wall, hits it, then keeps rolling.  But at the end of the ball's travels, it stops.  This is not because I manually stopped it with my hand off screen, but simply because an outside unbalanced force.  In this particular scenario, the force is gravity and that is why it stops.  

Projectile Motion

     Projectile motion is the motion in which a projectile travels.  If we know enough about a projectile, we can estimate things like the landing spot of the projectile or even the speed at which the projectile was launched.  We see projectiles a lot in our everyday lives especially in the world of sports.  Baseball, basketball, football, and soccer are sports in which angles and speeds of projectiles are adjusted to accurately launch the ball where you want.  

 

     In the picture above, the Quarterback is shown throwing a ball.  This relates to projectile motion because in order for the ball to accurately reach the receiver, it has to be thrown at a certain angle, with the correct amount of velocity.  Otherwise it would result in an inaccurate pass attempt.  

Relative Motion

     All motion is relative.  This means that even though a car moves at 50m/s, if another car is also going 50m/s then relative to each other the cars are really not moving.  However to the ground it is going 50m/s.  But what happens when one car is going 5 m/s but at the same time, a car in the opposite direction is going 10m/s?  This means that when the cars pass each other, relative to each other they are actually seeing the other car go 15m/s in the negative.  This can apply in the real world when we watch baseball.  

      If the pitcher throws the ball at 42m/s and the batter swings his bat at 38m/s then when the bat meets the ball, they are actually meeting at 80m/s.  This is because the ball is going 42m/s in the opposite direction in which the bat is being swung.  This results in an 80m/s collision.  

Projectiles

     A projectile that is launched into the air and is only affected by gravity.  One example of a projectile is a ball much like this.  

     Once this ball is thrown it becomes a projectile.  As soon as it is launched, there is nothing that affects it except for gravity. The motion of the ball is then a parabola because it will go up then gravity will eventually draw it back down.  

     However, the balls acceleration is always zero in the x-axis but its acceleration on the y-azis is 9.8m/s2 down which is the acceleration of gravity.

Vectors

     This past week in physics we learned about vectors.  A vector is a quantity that involves both direction and magnitude.  The way we add vectors is by measuring from tail to tip.  An example of that in a real life situation is in football.  

     When a receiver runs a route, he is running a vector.  If he runs straight 10 yards, then two yards back then the distance that the ball would travel is 8 yards and thats how to add two vectors together with each other.  

Quarter 1 Summary

Quarter 1 Summary

In the first quarter of physics we have learned many things.  The firs thing we have learned was the importance of standards, and more specifically the standards in measurements.  We used an example from old Hawaiian measurements like the pia which is the distance from your extended thumb to your extended pinky.  Another thing we learned was kinematics and motion.  All motion is relative.  So in order to know if something is moving, the question is always, “relative to what?”.  If two cars are going the same speed, they are not moving relative to each other but relative to the road, it is defiantly moving.  Another thing I learned is that the acceleration on Earth is 9.8m/s2.  We also learned the correct way to create a position vs. time graph, a velocity vs. time graph, and acceleration vs. time graph.  We learned how to calculate displacement from a graph and how to sketch the three graphs from information given by the other graphs.  Also we learned about pendulums and periods of time.  We learned how mass and length affected the time it would take the pendulum to swing back and forth five times.  Overall this is the major things we have learned in physics this year.  

Introduction

My name is Keenan and i am a student at Kamehameha Schools.  I have been at Kamehameha since kindergarten.  I really enjoy science as it is one of my favorite subjects.  In science courses thus far, I have been achieving great things.  I believe that I have learned a lot and I have achieved good grades.  I am currently in algebra 2a. From this course, I hope to achieve a greater understanding of physics and how it applies to the real world.

This is a picture of my sister and my little cousin.  This represents me as an individual because it shows that I am a happy person, who likes kids, and that I love my family.  This is a picture at the ice palace for someones birthday.  

Acceleration

       Acceleration is defined as the rate or speed of something.  If a car is accelerating at 1m/s then in 10 seconds, it will be going 10m/s.  When something is accelerating, it means that it is constantly getting faster or slower as long as the acceleration is not zero.

        If I were to drop this ball, its acceleration would be 9.8m/s because that is the acceleration of gravity.  So after 2 seconds the ball will be accelerating at 19.6m/s.  This ball would continue to get faster and faster.

Kinematics #3

          In this unit of kinematics, we learned about displacement.  Displacement is not how far you traveled, but how far you traveled from your starting point at any given time.  Throughout one day, no matter how far you go, if you return to where you started your day, your displacement is zero.

          The series of pictures above is an example of displacement.  The hermit crab at the bottom of the picture travels about three inches to the right but suddenly goes back to the starting point.  So he traveled approximately 6 inches but his displacement is zero because he returned to the original starting point.

Kinematics #2

Kinematics is seen everyday and in almost everything. A great example of motion is the dots dots we see on the road.

Are they moving? Relative to the road, no.  However, relative to us they appear to be moving backwards. To be able to say what is moving is dependent on what is relating to what. If two things travel at the same speed, they are not moving relative to each other. ALL MOTION IS RELATIVE!

Kinematics

      Kinematics is the branch of mechanics associated with motion.  All motion is relative.  Two cars going 40mph are moving, relative to the road.  However, the two cars are not moving relative to each other.  Below is an example of motion.

    The fan above is completely still.  It is not moving relative to the room.  However, when I turn the fan on, 

suddenly, the fan blades, relative to the room, is in rapid motion.  The neat thing about motion is that it is always relative.  While the fan blades are spinning around in circles, they are not moving relative to each other.  Since they are moving at the same speed, relative to each other, there is no motion involved.

"Standards In Measurements"

      The first thing we covered this semester in Physics was the importance of standards and how Hawaiian measurements related to it.  Measurements like the iwilei or pia are some ways of measuring using your body.  Iwilei is the length from your collar bone to the tip of your middle finger.  A pia is the length from your extended thumb to your extended pinky.  I recently went fishing and was fortunate enough to bag several fish.

       In order to measure it's estimated length, we used a pia to measure the length of this Black Tail Snapper, or To‘au.  This To‘au measured out to be about 11/3 pia or about 8".  This relates to our physics unit on Hawaiian measurements and standards because I used my knowledge of pia and measuring with my body to apply the measurements to my catch.