Circular Motion

A ball suspended by a thread swings in a vertical plane, so that its acceleration in the extreme position and lowest position are equal. The angle $\theta$ of thread deflection in the extreme position will be

A cone filled with water is revolved in a vertical circle of radius \(4 \mathrm{~m}\) and the water does not fall down. What must be the maximum period of revolution?

A train has to negotiate a curve of radius \(400 \mathrm{~m}\). By how much should the outer rail be raised with respect to the inner rail for a speed of \(48 \mathrm{~km} / \mathrm{h}\) ? The distance between the rails is \(1 \mathrm{~m}\)...