PHYA11H3 Lecture 20: [PHYA11][Lec 20]-[Chap. 10.4-10.7_ Restoring Forces, Elastic Potential Energy, and Energy Diagrams]

14.74 ... An object with mass 0.200 kg is acted on by an elas- tic restoring force with force constant 10.0 N/m. (a) Graph elastic potential energy U as a function of displacement x over a range of x from -0.300 m to +0.300 m. On your graph, let 1 cm = 0.05 J vertically and 1 cm = 0.05 m horizontally. The object is set into oscillation with an initial potential energy of 0.140 J and an initial kinetic energy of 0.060 J. Answer the following questions by refer- ring to the graph. (b) What is the amplitude of oscillation? (c) What is the potential energy when the displacement is one-half the amplitude? (d) At what displacement are the kinetic and potential energies equal? (e) What is the value of the phase angle • if the initial velocity is positive and the initial displacement is negative?

A scallop forces open its shell with an elastic material called abductin, whose elastic modulus is about 2.0 multiplied by 106 N/m2. If this piece of abductin is 2.7 mm thick and has a cross-sectional area of 0.60 cm2, how much potential energy does it store when compressed 1.1 mm?