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Name________________________________ J# _______ Newton Centers Prequel Answers - Honors Beginning tomorrow, you will be working in centers, in the order specified by Mrs. Twedt. Each center contains a Web Quest, and some contain explorations. Both today and tomorrow, you will go to www.mrs-twedt.com on your computer. GO to the resources tab and, today, click “Newton Centers Webquest PREQUEL.” Here, you will find a page that looks just like this sheet. You need to be sure you complete this sequentially. Whenever you see underlined text, it is a hyperlink to a website full of content I expect you to read. Then answer the question where you clicked the hyperlink on your paper. Today, we are reviewing MECHANICAL ENERGY since we know that FORCES cause changes in amounts of potential and kinetic energy, thus forces cause MOTION. NOW, go to www.mrs-twedt.com! StartWhat is the difference between kinetic and potential energy? Yes….you know this, I know that! ….BUT, let’s review. Explain it in terms of a roller coaster. (Read from the beginning, be sure to watch the animation, and make sure you include where the tracks come in to answer this!). There is a blank space to draw a diagram. Remember, As KE goes up, PE goes down (and vice versa). TME is the TOTAL mechanical energy in a system. It is KE + PE and it NEVER changes unless there are outside forces! You are familiar with both of these: Potential Energy and Kinetic Energy. According to the text written below the heading “Gravitational Potential Energy” on this page, Gravitational Potential Energy is The energy stored in an object as the result of its vertical position or height. The energy is stored as the result of the gravitational attraction of the Earth for the object. Use that same page to fill in the following blanks: “The gravitational potential energy of the massive ball of a demolition machine is dependent on two variables the mass of the ball and the height to which it is raised. There is a direct relation between Gravitational Potential Energy and the Mass of an object; more massive objects have greater gravitational potential energy. There is also a direct relation between Gravitational Potential Energy and the Height of an Object; the More that an object is elevated, the greater the GPE. These relationships are expressed by the following equation:” PEgrav = mass • g • height PEgrav = m *• g • h Another way to look at this is: Potential Energy (unit is Joules) = Weight x Height (since Mass x gravity (9.8) = weight) *However, you know that we rarely look at WEIGHT in science in the way that YOU know weight. In Science, Weight is looked at as a force (because it includes gravity). It is even given the unit Newton! Practice- *NOTE, mass is always in kg, so be sure to look at units! A 0.30 kg model airplane is hanging from the ceiling in a child's room. The airplane is hanging 2.50 m above the floor. If the floor is the position 0, what is the potential energy of the model airplane due to gravity? Show your work. Include your unit! Mass= .3 kg Gravity = 9.8 m/s2 Height = 2.5 m GPE = 7.35 J Caroline who has a mass of 5000 g, is about to jump off the back of the slide at the park. It is 3.25 meters high! If the ground is the position 0, what is her gravitational potential energy? Show your work. Include your unit! Mass= .5 kg (because 5000 g is .5 kg) Gravity = 9.8 m/s2 Height = 3.25 m GPE = 15.9 J *Continue reading and scroll down to the “Quick Quiz” with the stairs and make sure you can calculate! Kinetic Energy—Read the paragraph beginning with Kinetic Energy is the energy of motion. What is the formula used to represent Kinetic Energy? *What are the variables that determine the amount of kinetic energy? (explain what the letters above stand for!). m = mass of object v = speed of object What is their relationship? *Meaning, explain the equation. I’ll start you… For every twofold increase in speed, the kinetic energy will increase by a factor of four. For a threefold increase in speed, the kinetic energy will increase by a factor of nine. And for a fourfold increase in speed, the kinetic energy will increase by a factor of sixteen. The kinetic energy is dependent upon the square of the speed. SO, do you understand? Prove it. I have a marble with a mass of .0032 kg. It rolls down a ramp at a speed of 2.4 m/s. How much kinetic energy does my marble possess? Show your work. Include your unit! KE = (.5) x (.0032 kg) x (2.4 m/s2) .0092 J A roller coaster cart with a mass of 500 kg is speeding down the track at 53 m/s. How much kinetic energy does the coaster car have? Show your work. Include your unit! KE = (.5) x (500kg) x (53m/s2) 702,250 J Is Kinetic Energy a scalar quantity or a vector quantity? Kinetic energy is a scalar quantity; it does not have a direction. Unlike velocity, acceleration, force, and momentum, the kinetic energy of an object is completely described by magnitude alone. *Note, though V is used in the formula, speed is the variable used, not direction. This makes it scalar.