1. The problem statement, all variables and given/known data A simple pendulum is 5m long. What is the period of the oscillations for this pendulum in an elevator accelerating upwards at 5m/s2 and accelerating downards at 5m/s2 2. Relevant equations ω = √(g/L) T = 2∏ / ω 3. The attempt at a solution I got the right answers (trial and error), although I don't understand the concept. for accelerating upwards. ω = √[(9.8+5) /5] ω = √[(14.8) /5] ^----this above part is confusing to me. If gravity is pointing down, and we have upward acceleration, shouldn't the value of (g + a) be smaller? I don't understand the meaning of 14.8 m/s2 I think the way the equation is defined confuses me. ω = √(g/L) the algebra of the equation doesnt confuse me, I understand why g can not be negative because of the root. However, if gravity always points down, and we let gravity be positive 9.8m/s, shouldn't and upward acceleration be defined as pointing in the negative direction? thus shouldn't it be : ω = √[(9.8m/s2 MINUS 5m/s2) /5] ?? can someone explain the sign conventions? I have confused myself.