Please help me with these questions:

1. If the kinetic energy of a mass (7.11x10^-2) kg is (5.120x10^0) kJ, what is the speed of the object in m/s? Use 2 sf in your answer.

2. A spring with a spring constant of (3.944x10^4) N/m is stretched from an initial extension of (9.49x10^-2) m to a final extension of (3.075x10^-1) m. Calculate the work that must be done by the external force. Give your answer to 2 s.f.