Question

An object is launched at an angle of 78º above the horizontal with an initial speed of 120 m/s. Find (a) the maximum altitude reached by the object, (b) its total time of flight, and (c) its horizontal range

Answer 1

V1= 120m/s[78o].
X1 = 120*Cos78 = 24.9 m/s.
Y1 = 120*sin78 = 117.4 m/s.

a. Y2^2 = Y1^2 + 2G*h.
0 = 117.4^2 - 19.6h, h = ?.

b. V2 = V1 + g*Tr.
0 = 117.4 - 9.8Tr, Tr = 12 s. = Rise time.

Answer 2

h = 0.5g*Tf^2 = 703 m.
4.9Tf^2 = 703, Tf = Fall time = ?.

Tr+Tf = Time in light.

c. Range = X1*(Tr+Tf).