a uniform half metre rule AB is balanced horizontally on A knife-edge placed 15 cm from A and with the mass of 30 gram at A what is the mass of the rule

answer is 45 is correct answer

jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.

your answer is c! hope this : )