A gymnast jumps straight up, with her center of mass moving at 2.90 m/s as she leaves the ground. How high above this point is her center of mass a) 0.100 s, b) 0.200 s, c) 0.300 s and d ) 0.500 s thereafter? (a: 0.241 m, b: 0.384 m, c: 0.429 m, d: 0.225 m)