Question

an object is projected at an angle of elevation of 45 degree with a velocity of 100m/s.calculate its range and time of flight

Answer 1

up for time t then down for time t (parabola)
u = 100 cos 45 forever
Vi = 100 sin 45 at start

v = Vi - g t
at top v = 0
so
at top t = Vi/g = 100 sin 45 / 9.81

in the air for time = 2 t
so
range = 2 t u = 2 t (100 cos 45)

Answer 2

Time of flight formula
=2×100/9.8
=20.40s

Range formula
=100×100÷9.8
=1020.4
=10.2m