A pendulum bob has potential energy U₀ when held taut in a horizontal position.The bob falls until it is 30° away from the horizontal position,when it has potential energy U_A.It continues to fall until the string is vertical,when it has potential energy U_B.Compare its potential energies at O,A,and B. A)U₀ = U_A = U_B. B)U_A − U_B = 2U₀. C)U_A − U_B = U₀ − U_A. D)U₀ = U_B = 2U_A. E)U₀ − U_A = 2(U_A − U_B).

Question

Quizplus · Accepted Answer

At point O, the bob has its maximum potential energy, which is given as U₀. As it falls and reaches point A, it has lost some potential energy, which is given as U_A. Similarly, at point B, it has lost even more potential energy and has only U_B left. Therefore, U₀ is the maximum potential energy of the system, and at any point below it, the potential energy will be less. Therefore, U_A is less than U₀, and U_B is less than U_A. Hence, the difference between the potential energies at points A and B is less than the difference between the potential energy at point O and point A. Therefore, the correct choice is C.

A Pendulum Bob Has Potential Energy U0 When Held Taut

A Pendulum Bob Has Potential Energy U₀ When Held Taut