Q4 of 43 Page 85

The position coordinates of a projectile projected from the ground on a certain planet (with no atmosphere) are given by y = (4t – 2t2) m and x = 3t m where t is in seconds and point of projection is taken as origin the. The angle of projection of projectile with vertical is:-

a) 30° b) 37° c) 45° d) 60°

Given: ...1

x = 3t m ...2


Now, velocity is given by:


..3


Where, = Velocity component along x – axis


And, = Velocity component along y – axis


Now,


So, = 3 ms–1 ..4


Similarly, ms–1 ..5


Initial velocity at t = 0 is


So, putting t = 0 in 4 and 5, we get:


= 3 ms–1 and = 4 ms–1



Here,


Ɵ = Angle of projection with vertical


So,




Hence Ɵ = 37°


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