The sun is stable because the force of gravity is balanced by the thermal pressure created by the reactions in its core. the sun will remain stable a) as long as the outer surface of the sun remains solid b) as long as there is a sufficient source of energy within the sun. c) as long a the planets continue orbiting the sun d) as long as the gravity of jupiter does not act on the sun

To place a communications satellite into a geosynchronous orbit at an altitude of 22,240 mi above the surface of the earth, the satellite first is released from a space shuttle , which is in a circular orbit at an altitude of 185 mi, and then is propelled by an upper-stage booster to its final altitude. as the satellite passes through a, the booster's motor is fired to insert the satellite into an elliptic transfer orbit. the booster is again fired at b to insert the satellite into a geosynchronous orbit. knowing that the second firing increases the speed of the satellite by 4810ft/s, determine (a.) the speed of the satellite as it approaches b on the elliptic transfer orbit, (b.) the increase in speed resulting from the first firing at a.