question_answer 39)

A 70 kg man stands in contact against the wall of a cylindrical drum of radius 3 m rotating about its vertical axis with . The coefficient of friction between the wall and his clothing is 0.15. What is the minimum rotational speed if the cylinder to enable the man to remain stuck to the wall (without falling) when the floor is suddenly removed ?  

Answer:

Here The horizontal reaction R of the wall on the man provides the necessary centripetal force.               The frictional force  acting vertically upwards balances the weight of the man. The man will remain struck to the wall after the floor is removed, if   or                                 or             or The minimum rotational speed of the cylinder is