What came first the chicken or the egg

What are similarities and differences of reflection, refraction, diffraction and absorption?

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.

Often called simply "velocity," this is the velocity of an object at a particular moment in time.