Asmall toy cart equipped with a spring bumper rolls toward a wall with a speed of v . the cart rebounds from the wall, with the same speed v . the sketch below shows the initial velocity vector v⃗i , final velocity vector v⃗f , and the initial momentum vector p⃗i . using the initial momentum vector as a basis, draw the change in momentum vector δp⃗ for the cart.

the orientation and length of your vector will be graded. the location will not be graded.

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.