work and energy?

Question

1] the moon has a mass of 7.4 x 10^22 kg and completes an orbit of radius 3.8 x 10^8 m about every 28 days. The Earth has a mass of 6 x 10^24 kg and completes an orbit of radius 1.5 x 10^11 m every year. What is the speed of the moon in its orbit?

2] what is the kinetic energy of the moon in orbit?

3] what is the kinetic energy of the earth?

Answer 1

1) The circumference of the moon's orbit is 2 X pi X radius and the speed of the moon in orbit is given by circumference / time

2) Kinetic energy is 1/2 X mass X velocity^2 (speed is the magnitude of the velocity and can be used here)

Please do the calculations yourself.