an object of mass 30 kg is falling in air (a=9.8m/s^2) and experiences a force due to air resistance of 50 newtons. Determine the net force acting on the object and calculate the acceleration of the object

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.