Q1. A 1000kg experimental rocket sled at rest on level frictionless rails is loaded with 50kg of propellant. It exhausts the propellant in a 20 s "burn." The rocket moves at 150m/s after the burn. What average force is experienced by rocket during the burn?

Q2. On the sunlit surface of Venus, the atmospheric pressure is 9.0 × 10^6 Pa and the temperature is 740K. On the earth's surface the atmospheric pressure is 1.0 × 10^5 Pa, while the surface temperature can reach 320K. These data imply that Venus has a "thicker" atmosphere at its surface than does the earth that means that the number of molecules per unit volume (N/V) is greater on the surface of Venus than on the earth. Find out the ratio (N/V) Venus / (N/V) Earth.