A block is attached to a non–linear spring and moves in 2D. The energy function of the block is given by
U(x, y) = 6.00yx − 4.50xy^3
(a) What are the units of the constants?
(b) Assuming the mass of the block is 0.500 kg, what is the acceleration of the block at (x, y) = (0.250, 0.500)?