Solve the all parts of following problem given below:
Problem: A mass on a string of unknown length oscillates as a pendulum with a period of 3.0s. What is the period if-
Part I: The mass is doubled?
Part II: The string length is doubled?
Part III: The string length is halved?
Part IV: The amplitude is doubled?
I need help to solve the above problem and all Parts I to IV are independent questions, each referring to the initial situation.