A body crosses the topmost point of a vertical circle with critical speed. What will be its centripetal acceleration when the string is horizontal.
Step1: Given data
The object at the top of the vertical circle has a speed equal to critical speed.
Step2: Formula used
The critical speed at the top of a vertical circle,
At a point in a horizontal circle, when the string becomes horizontal, the speed of the object,
Step3: Calculating the final speed.
According to the given data, the speed of the object at the topmost point
This will act as the initial speed for when the string becomes horizontal i.e.
Therefore the speed of the object at this point will be
The change in height of the object from the initial point is equal to,
Step4: Calculating centripetal acceleration
The centripetal acceleration when the string becomes horizontal is 3g.
Hence, option C is the correct answer.