Trolley A, of mass 180 g, is moving at a velocity of 4 m/s towards trolley B which is stationary and has a mass of 120 g. Trolley A then collides with
trolley B.
Calculate the speed of trolley B if:
i the collision is elastic (trolley A stops and trolley B moves off)

Four point charges each having charge q are located at the corners of a square having sides of length a. find symbolic expressions for the following. (a) the total electric potential at the center of the square due to the four charges (use any variable or symbol stated above along with the following as necessary: ke.) vtotal= (b) the work required to bring a fifth charge p from infinity to the center of the square (use any variable or symbol stated above along with the following as necessary: w=