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Physics Section 5.3 Solve conservation of energy problems. Mechanical Energy – sum of all kinetic and potential energy. Conservation of Mechanical Energy In the absence of friction, the total mechanical energy of a system remains constant. PE elastic + KE + Pe gravitational
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Physics Section 5.3Solve conservation of energy problems Mechanical Energy – sum of all kinetic and potential energy
Conservation of Mechanical EnergyIn the absence of friction, the total mechanical energy of a system remains constant. PEelastic + KE + Pegravitational ½ k(xi)2 + ½ m(vi)2 + mghi = ½ k(xf)2 + ½ m(vf)2 + mghf A rock with a mass of 4.5 kg is dropped from a height of 2.5 m. Find its velocity just before it strikes the ground.
example An eagle is flying with a speed of 18.0 m/s over water when it accidentally drops a 2.00 kg fish. If the altitude of the eagle is 5.40 m and friction is disregarded, what is the speed of the fish when it hits the water? ½ k(xi)2 + ½ m(vi)2 + mghi = ½ k(xf)2 + ½ m(vf)2 + mghf
example An Olympic runner leaps over a hurdle. If the runner’s initial vertical speed is 2.2 m/s, how much will the runner’s center of mass be raised during the jump? ½ k(xi)2 + ½ m(vi)2 + mghi = ½ k(xf)2 + ½ m(vf)2 + mghf
assignment Page 178 Problems 1,2,3