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A bob is pulled side way so that string becomes parallel to horizontal and released. Length of the pendulum is 2 m. If due to air resistance loss of energy is 10%, what is the speed with which the bob arrived at the lowest point. |
Answer» Given, Potential energy of pendulum is converted into kinetic energy and lost energy in air. So, PE = KE + lost energy......................(1) According to question, lost energy = 10% of PE =0.1PE Eqn (1) becomes PE = KE + 0.1PE => 0.9PE = KE =>0.9 mgh = 0.5 mv => 0.9 gh = 0.5 v => v = 1.8gh v = speed at the lowest point. h = length of pendulum = 2m g = 9.81 m/s Plug in the values of g and h v = 5.94 m/s |
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