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Mental Health Report
I know I say it every week but this week was stressful! For once, the stress had very little to do with the class itself. Since I work for a city Parks & Recreation dept. I was extremely busy this week with preperations for our biggest event of the year, the 4th of July. I have never had a class at the same time I was getting ready for the 4th so I had no idea how much time it really demanded. Thankfully, this weeks concepts and work were easy for me to grasp and use. While I did spend two hours trying to figure out why my calculations weren't coming out right (I forgot to convert my feet to meters), that was really the only set back I had this week. Unfortunately, next week will likely be just as stressful since I have to go out of town for a wedding on Thursday and I doubt I will have much time to do class work!
Screen Jelly #6
Screen jelly #7
This video perfectly demonstrates the ways in which energy transforms and changes within a system and illustrates the law of the conservation of energy. No energy within a system is ever created or destroyed, only transformed. In the beginning, coyote stretches the tightrope by holding onto an anvil, this is his way of putting work into the system that is then converted into potential energy. When he lets go of the anvil the potential energy is again trasnformed into kinetic energy and he is launched into the air. As he flies up, that kinteic energy is steadily being transformed into gravitational energy and when the two are equal in force he hangs in the air a split second until gravitaional force becomes greater than kinetic and he begins to fall again.
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How does Hooke's Law and acceleration affect launch? Here is what I learned...
During the launch portion of the motion Newton’s first and third laws are most apparent. The marshmallow remains at rest in the launcher’s bucket since the only force acting on it is the pull of earth and the launcher itself. His first law states that an object at rest will stay at rest until a (net) force is applied. This net force can be calculated using Hooke’s Law. F=kx allows us to find out how much force is exerted on the mallow and this in turn helps us estimate it’s velocity, acceleration and range. In the case of one of our team’s launchers, Hooke’s Law told us that it could apply a force of around 216N. The moment the launching mechanism is triggered Newton’s third law comes into play. The force generated by the motion of the launcher is large enough to give the mallow motion but even so the marshmallow pushes just as hard against the launcher as it is leaving the bucket. Since the mass of the launcher is significantly more than the mass of the mallow, the mallows force on the launcher is overcome and it is sent flying. For every action there is an equal and opposite reaction, even if the force and motion of one object causes the movement of the other.
During the launch we also wanted to know the acceleration of our mallows. So, using the force we calculated from Hooke’s Law and the velocity of our mallow, we could use the formula Vf^2=Vi^2+2ax. By rearranging it to solve for a, we discovered that the acceleration of our mallow launcher was ~2867m/s/s. To do this we could have also used Newton’s 2nd law (F=ma). However, I am still not sure what the average mass of a single mallow is and my bathroom scale wasn’t as accurate as I would have liked.
Hooke’s Law states that F=kx or that “The extension of a spring is in direct proportion with the load added to it.” (www.wikipedia.com) In this equation F is the force exerted by the rubber bands when they resist being stretched. The spring constant is the amount of stretch ability within a system or material. In this case, our rubber bands are the springs. Mathematically, the spring constant is the slope of the line of units of force per unit of length. Our x value is the displacement of the end of the spring (rubber band) from its equilibrium. In simple terms, what is the difference in length between its stretched and relaxed states? When two of these values are known, the third can be determined. In our case, we discovered that when our spring is stretched .85m with a spring constant of 85 newtons, we will create 216 newtons of force.
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