Masses `M_(1), M_(2)` and `M_(3)` are connected by strings of negligible mass which pass over massless and frictionless pulleys `P_(1)` and `P_(2)` as shown in the figure. The masses move such that the portion of the string between`P_(1)` and `P_(2)` is parallel to the inclined plane and the portion of the string between `P_(2)` and `M_(3)` is horizontal. The masses `M_(2)` and `M_(3)` are 4.0 kg each and the coefficient of kinetic friction between both the masses and the surfaces is 0.25. The inclined plane makes an angle of 37° with the horizontal. If the mass `M_(1)` moves downwards with a uniform velocity, find
(i) the mass of `M_(1)` in kg
(ii) the tension in the horizontal portion of the string in Newton

Explanation

(i) Thecodont: It is the condition in which teeth are present in the sockets.
(ii) Diphyodont: It is the condition in which teeth appear in two sets---- milk teeth and permanent teeth. In human beings, there are 20 teeth in milk set while 32 teeth in permanent set.