Topic - Advanced Physics Lab



00Non-Conservation of Mechanical Energy Non-Conservation of Mechanical Energy Seed Question: What can you do if Wnc ≠ 0? What do you think Wnc equals?Exploration: Write down the Big Idea first and use it to do answer the following questions.1. Look at the kid who set up the water slide that unfortunately ends on a horizontal brick surface. How far x do they slide across the brick surface? Find x in terms of μk, and h.2540136525hmhm2. You (m = 65 kg) are riding a skateboard and are put in a giant sling-shot that is pulled back a distance x = 1.5 m. k = 95,000 N/m. This time assume you experience a nearly constant force of air drag of 750 N that acts over a distance of 90 m. How high up (h) will you go?2863855715h = ?mh = ?m3. You (m = 65 kg) step off a 10 m high dive platform, falling into a pool of 30,000 L of water. How much does the temperature of the water increase? Use the specific heat of water c = 4,187 J/(kgK).Big Idea: To Do All Energy Problems:Step 1: (Same as before) Sketch the problem. Sketch and label the initial and final positions of the object and draw in vo and vf. Decide where to make the ------reference level for gravitational potential energy and mark it, then indicate in ho and hf.Step 2: Is Wnc = 0 ? If yes, then:If no, then: Eo = EfWnc = ΔE Ko + Uo = Kf + UfWnc = Ef - Eo Wnc = (Kf + Uf ) – (Ko + Uo)…Substitute all the formulas in for K and U…Step 3: Solve for the missing variable. (Pretty straightforward, no?)Mechanical Energy can be transformed into heat energy: ΔE = -Q. Ex: a block slides to rest across a rough horizontal surface. The force of kinetic friction does negative work, and the mechanical energy of the system turns into heat energy: Wnc = ΔE = -Q. The Mechanical Equivalent of Heat states:Q = cm ΔT where Q is the heat energy c is the specific heatm is the mass ΔT is the change in temp Discussion: ? ................
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