Question

20. At what height above the earth's surface. the acceleration due to gravity will be 1/9th of its value at the earth's surface. Re = 6400km ​21. If the radii of the two planets be r1 and r2 and their mean densities d1 and d2. then prove that the ratio ofacceleration due to gravity on the planets will be r1d1: r2d2. 22. If earth has a mass 9 times and radius twice that of planet mars, calculate the minimum velocity required by a rocket to pull out gravitational force of mars. The escape velocity on the earth's surface is 11.2 km/s. 23. Calculate the escape velocity on the earth's surface. Take Re= 6.4 X 108cm and g = 9.8m/s2. 24. Calculate the velocity with which a body prjected from the surface of the moon may escape from its gravitational pull. Mass of moon = 7.5 X 1022 kg , R of moon = 1.6 X 106 and G = 6.67 X 10-11 Nm2kg-2. 25. What will be the value of 'g' on the moon surface if its radius were 1/4ththe radius of earth and its mass is 1/80ththe mass of earth. 26. The radius ofthe planet is double that ofthe earth but their average densities are the same. If theescape velocities of the planet and the earth are vp and ve respectively. then prove that vp=2 ve. 27. A body of mass 10kg falls on the earth from infinity . What will be its velocity on reaching the earth. Also calculate the energy acquired by the body on reaching the earth. Re = 6400km. g= 10 m/s2 and Neglect the friction. 28. How much energy would be needed for a body of mass 10kg to escape from earth? g = 10m/s2 and Re = 6400km.

Answer 1

5 inches... why? I don't know... but it is...! You can look high up there in the sky and you'll see what I said. You are Welcome!