Hey physics forums, this is my first post and frankly I'm having trouble conceptualizing this problem. I know harmonic oscillation is involved, as it is a pendulum. However, I know I have to incorporate g into the s.h.o. equation and I'm not quite sure how to do that. Any help would be greatly appreciated. 1. The problem statement, all variables and given/known data A pendulum clock which keeps correct time at a point where g=9.8 m/s^2 is found to lose 10 seconds per day at a higher altitude where the gravitational field now has a new value g(n). What is the numerical value of this g(n)? 2. Relevant equations This is from the force diagrams I've drawn. Tcos(theta)-mg=ma(x) Tsin(theta)=ma(y) I'm lost. Please help!