Determine the centre of gravity of a uniform or irregular object using balance and moment principles.
A pendulum consists of a solid sphere suspended by a string from a fixed point P , as shown in Fig. 3.1.
Fig. 3.1 (not to scale)
The sphere swings from side to side. At one instant the sphere is at its lowest position X , where it has kinetic energy 0.86 J and momentum 0.72 Ns in a horizontal direction. A short time later the sphere is at position Y , where it is momentarily stationary at a maximum vertical height h above position X.
The string has a fixed length and negligible weight. Air resistance is also negligible.
State and explain whether the sphere is in equilibrium when it is stationary at position Y .