Posted by help on .
the horizontal range of a projectile is 4 root 3 times of its maximum height. calculate the angle of projection.

11th grade physics 
Anonymous,
Let 'x' be the angle of projectile with the horizontal.
Then,taking g=10m/s^2:
Given, Hmax=[(usinx)^2]/2g;
R=4(root of 3)x(Hmax);
R=[(u^2)(sin2x)]/g;
Thus,
(u^2)sin2x 4(usinx)^2
 = 
g (root of 3)2g
Then,upon simplification:
sin2x 2(sinx)(sinx)
 = 
1 (root of 3)
2sinxcosx 2
 = 
sinxsinx (root of 3)
cosx 1
 = cotx = 
sinx (root of 3)
So,x=60 degrees. 
11th grade physics 
Heerthana,
It is not correct book answer