The time delay between transmission and the arrival of the reflected wave of a signal using ultrasound traveling through a piece of fat tissue was 0.13 ms. At what depth did this reflection occur? (The average propagation speed for sound in body tissue is 1540 m/s)

Four objects each with charge +2.0×10−7c are located at the corners of a square whose sides are 2.0 m long. part a what quantities can be determined using this information? check all that apply. the electric force on a charged object placed at the center of the square. the mass of each object. the total electric potential energy of the system consisting of the four charged objects. part b find the electric force on a charged object placed at the center of the square.