The mean diameters of planets A and B are 9.8 x 103 km and 2.6 × 104 km, respectively. The ratio of the mass of planet A to that of planet B is 0.93. (a) What is the ratio of the mean density of A to that of B? (b) What is the ratio of the gravitational acceleration on A to that on B? (c) What is the ratio of escape speed on A to that on B? (a) Number i (b) Number i (c) Number i Units Units Units

On February​ 15, 2013, Asteroid 2012 DA14 passed within​ 17,200 miles​ [mi] of the surface of the Earth at a relative speed of 7.8 kilometers per second​ [km/s]. This is considerably closer than the orbit of geosynchronous satellites​ (26,200 miles). This is the closest recorded approach of an object this large. The asteroid 2012 DA14 was estimated to have a diameter of 30 meters​ [m] and a specific gravity of 3. If 2012 DA14 had hit the​ Earth, what is the total amount of energy that would have been released​ (i.e., what was the kinetic energy of the​ asteroid)? Express your answer in megatons​ [Mton]. One megaton is the energy released by one million metric tons of TNT explosive. A metric ton equals​ 1,000 kilograms​ [kg], and the explosive energy of TNT is 4,184 joules per gram​ [J/g].

Rick is an Aerospace Engineer at NASA’s Jet Propulsions Laboratory (JPL), and is designing the next mission to Pluto called “New Horizons 2: The Sequel". This time Rick plans to study Pluto's largest moon Charon. Charon has a mass of 1.586 ×1021 kg and a mean radius of 606 km, and might have a nitrogenous atmosphere (N2) just like Pluto. If, for a massive object to have an atmosphere its escape speed must be 12 times greater than the root-mean- square (rms) velocity of the gas (otherwise the gas will slowly leak away over time), what is the maximum temperature that Charon can have and still have a nitrogenous atmosphere? [Charon has a temperature of -281 °C = 55 K, day or night.]

Venus is known as the 'Earth's sister' because of its similar size and gravity. It has a mass of 4.87 x 10^24 kg and an average radius of 6060 km. As the 150 kg satellite slowly approaches the surface of Venus it is influenced by its gravitational field. (a) Describe how the satellite gravitational potential energy changes as it is moving from an altitude of 5000 km to the surface of Venus.   (b) Calculate the gravitational fieid strength on the surface of Venus.