1. The problem statement, all variables and given/known data What would the period be if the pendulum had been inclined to 90 degrees? What value of g does this correspond to? theta=90degrees. Just as a side note, theta=0degrees when the arm is facing vertically downwards towards the ground. g=9.8m/s^2 Effective length=0.275m. The value of length was found from the lab I carried out. Mass attached to end of arm=0.176kg 2. Relevant equations T=2pi x root(L/gcostheta) T is period. ag=gcostheta. ag is acceleration due to gravity. 3. The attempt at a solution T=2pi x root(0.275m/(9.8 x cos90))=undefined. Since ag=gcostheta=(9.8 x cos90)=undefined, there would be no acceleration acting on the pendulum, thus no force pushing the pendulum. As a result, the pendulum will not oscillate, and there would be no period. I'm not sure if this is correct, would a pendulum still oscillate when the arm is tilted at 90degrees, and how can period be undefined?