gravitationaly 3 masses are placed in an equilatera triangle and at rest. what is the force acting on the topmost mass

What are atoms of the same element with varying number of neutrons

Which governments provide garbage collection services to homes and businesses

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.