question_answer

A small block is shot into each of the four track, as shown below. Each of the frictions, track rises to the same height. The speed with which the block enters the tracks, is same in all cases. At highest point of the track normal reaction is maximum in

A)          

B)  

C)  

D)  

Correct Answer: A

Solution :

As the block rises to the same height in all the four four cases, from conservation of energy, speed of the block at highest point will be same in all four cases say it is VQ. Equation of motion will be \[N+mg=\frac{mv_{0}^{2}}{R}\] or       \[N=\frac{mv_{0}^{2}}{R}-mg\] R (the radius of curvature) in first case is minimum \[\therefore \] Normal reaction N will be maximum in first case.