physics
posted by ally .
The initial kinetic energy imparted to a
0.72 kg bullet is 1777 J. The acceleration of gravity is 9.81m/s2.Neglecting air resistance, ﬁnd the range of this projectile when it is ﬁred at an angle such that the range equals the maximum height attained.
Answer in units of km.

First calculate the initial velocity Vo, using
(M/2)Vo^2 = 1777 J
If the range equals the maximum height,
2(Vo^2/g)sinA*cosA = (1/2)(Vo^2/g)sin^2A
2 cosA = (1/2)sin A
tanA = 4 A = 76.0 degrees
Use that angle in either the range or the max height formula