Two spheres with masses m = 800 kg and m = 510 kg are separated by 0.400 m. What is the net gravitational force from them on a 2.1 kg sphere located 0.280 m from m and 0.120 m from m? Use a + sign if the direction is towards m and a - sign if the direction is towards m On planet Zog, Mr. Spock measures that it takes 1.47 s for a mass to hit the ground when released from rest from a height of 2.73 m. Calculate the size of the acceleration of gravity on that planet. O