A 20 kg kangaroo is bouncing as kangaroos are wont to do. During a certain interval after the marsupial leaves the surface of the earth, its kinetic energy decreases from 440J to 210J. Assume your mathematical ground is at the lowest point in your interval. What is the kangaroo's kinetic energy at the lower point within the given interval? Do not include units on numerical answers. If you use scietific notation, then use the capital E to stand for x10^ . For example, 3.7x10^-2N would be entered as 3.7E-2 instead