A particle of mass `0.1kg` is launched at an angle of `53^(@)` with the horizontal . The particle enters a fixed rough hollow tube whose length is slightly less than `12.5m` and which is inclined at an angle of `37^(@)` with the horizontal as shown in figure. It is known that the velocity of ball when it enters the tube is parallel to the axis of the tube. The coefficient of friction betweent the particle and tube inside the tube is `mu=(3)/(8)[` Take `g=10m//g^(2)]`

The velocity of the particle as it enters the tube is `:`

Options

A. `12m//s`
B. `16m//s`
C. `9m//s`
D. `15m//s`

Answer

D

Explanation

The particle while entering has inclination of `37^(@)`. Let its velocity here be `V`.

Now `V cos 37^(@)= 20 cos 53^(@)` as horizontal component does not charge.
`:. V=20xx(3)?(5)xx(5)/(4) = 15 m//s`.