The trajectory of a projectile projected from origin is given by the equation `y = x - (2x^(2))/(5)` .The initial velocity of the projectile is

Options

A. 25 m `s^(-1)`
B. `2/5` m `s^(-1)`
C. `5/2 m s^(-1)`
D. 5 m `s^(-1)`

Answer

D

Explanation

(d): y= x `tan theta - 1/2 "g" (x^(2))/(u^(2)cos^(2)theta)`
Comparing with given equation
`tantheta = 1 rArr theta = 45^(@)`
`1/2 "g" (1)/(u^(2)cos^(2)theta) = 2/5 rArr u^(2) cos^(2) theta = (25)/(2) rArr u = 5`