let us consider a bob suspended by means of a thread from a fixed point (wrt ground and i m considering ground to be an inertial frame in this problem ) . What will be the time period of small oscillations of this pandulum as seen by a man accelerating with an acceleration a along the horizontal . will it be 2pi(root(l/g)) or will it be 2pi(root(l/root(a^2+g^2)) . logic1 : if we solve the problem in ground frame we get T=2pi(root(l/g)) . now at small speeds this time is not frame dependent , hence the time period should be same in mans frame also . logic2 : We want to calculate T as seen by man so lets solve the problem in mans frame . Since its a noninertial frame a pseudo force will act on the bob and the time period will come out to be 2pi(root(l/root(a^2+g^2)) . which one is correct ?