Tuesday, December 8, 2009

Newton's First Law

In this unit, I have learned about Newton's First Law of inertia. This law states that objects in motion stay in motion and objects at rest stay at rest unless affected by an outside force. We applied this to translational equilibrium, meaning that an object is at rest or in constant motion. Using this we could find the tension force acting upon an object hanging from multiple cables by setting the sum of the forces in the x and y axes, ∑Fx and ∑Fy, equal to zero and using algebra to isolate and solve for the variables. We also used FBD's to help visualize the forces acting upon an object.

One thing that I have struggled with was the trigonometry. Sometimes it is difficult to know the exceptions when using sine instead of cosine for the x-component or using cosine instead of sine in the y-component.

I have noticed that my problem solving skills have gotten much better. Even when I feel like I don't completely understand a concept I surprise myself by being able to solve the problem and enhance my understanding of the concept. For example, I am beginning to understand how to know the exceptions when using trigonometry for the x and y-components. During the translational equilibrium lab, with some help from Chris, I correctly used trigonometry in the force components.

Newton's First Law can be applied to many situations in the real world. If someone knows Newton's First Law of inertia, then they are much more likely to wear a seat belt because they know that if they are in motion they will stay in motion even if the car stops due to an outside force, and they won't stop until they are stopped by the force of the windshield. It can also be used when hanging a sign or object and one needs to know if the cables that they have will be able to support the weight. These are just few of the many examples of how Newton's First Law can be applied to the world.

Mrs. Gende, I am sorry that I didn't do the assignment, I forgot to check the website and hope that you like my reflection post.

Wednesday, November 11, 2009

Projectile Motion: When Water Balloons Fly

Projectile Motion

One day, I was walking home from school when suddenly I heard a loud smack behind me. I turned around to discover that a water balloon had hit the pavement. Then, trying to find out what direction the balloon came from, I saw another and ran to avoid being soaked. As I looked at the direction it came from, I saw a small group of 4 or 5 people with a water balloon launcher and a huge bucket filled with the balloons. I saw them pull back the launcher and one yelled “PULL!” and I saw the balloon approaching with great speed. I was terrified and began to sprint when my jacket caught onto the fence next to me and I was stuck. I was terrified and anxious on whether I would get hit because I was a sitting duck. The balloon barely missed me. Unfortunately, I was still stuck and they had already loaded another balloon. I knew that there was only one way to find out how much time I had to escape the fence was PHYSICS! Fortunately, I had Physics class that day and we had just learned about projectile motion. I remembered that I could find how long the projectile, in this case a speeding water balloon, was in the air. I knew that their last miss would have been a direct hit if they had aimed right and saw that the launcher was at the same angle. I would have to base how much time I had left on the last shot. I could tell that I was about 24m from where the balloons were being launched and that it was being launched at an angle of about 15m/s at 45˚ in relation to the horizontal. I quickly thought through all the ways that I could calculate the time: t = x/Vocosθ or t = Vosinθ/g. Knowing what I was given I quickly decided the fastest way was t = x/Vocosθ. So I plugged in the distance, x = 24m, divided by Vo = 15m/s*cos45˚ which all came out to 2.3s. Once I heard them shout “PULL!” again, I knew I needed to act fast. Finally I broke free from the fence and sprinted away dodging the water balloon at the last second all because of PHYSICS!

Projectile Motion Voki

Projectile Motion Wordle



Here are some commonly used words when dealing with projectile motion. I used www.wordle.com to make this.

Tuesday, November 10, 2009

Projectile Motion: When Water Balloons Fly... The Movie

GoAnimate.com: Physics project by thovyson69

Like it? Create your own at GoAnimate.com. It's free and fun!

Thursday, October 29, 2009