1. The problem statement, all variables and given/known data a ball was hanging by an inextensible string to a small airplane. firstly, it was hanging straight down but when the pilot started the motor the string made an angle of 30 degrees wrt the vertical. Assuming that the ball is a point mass, find the acceleration (m/s²) of the airplane (neglect air resistance) 3. The attempt at a solution While hanging at 30 degrees, the ball is constant, this means that the vectorial sum of forces is zero (newton's law), but I don't know what to do next !