57. . IP A pendulum bob with a mass of 0.13 kg is attached to a string with a length of 0.95 m. We choose the potential energy to be

zero when the string makes an angle of 90° with the vertical.(a) Find the potential energy of this system when the string makes an angle of 45° with the vertical. (b) Is the magnitude of the change in potential energy from an angle of 90° to 45°greater than, less than, or the same as the magnitude of the hange from 45° to 0°? Explain. (c) Calculate the potential energy of the system when the string is vertical.