In: Physics
A projectile is fired from the ground, reaches a maximum height of 26.8 m and lands a distance of 76.7 m away from the launch point. What was the projectile s launch velocity?
A) 28.2 m/s, 54.4 degrees above horizontal
B) 22.9 m/s, 27.2 degrees above horizontal
C) 16.4 m/s, 16.3 degrees above horizontal
D) 42.3 m/s, 8.2 degrees above horizontal
Maximum height, h = v2sin2
/ 2g ...(1)
Where v is the initial velocity,
is the launch angle
Horizontal range, R = v2 sin2
/ g ...(2)
(1) / (2) gives
h/R = (sin2
/ sin2)
* 1/2
= [(sin*sin)
/ 2sin*cos)]
* 1/2
= [tan]*1/2
= tan/4
tan
= 4h/R
= tan-1(4h/R)
= tan-1(4 * 26.8 / 76.7)
= 54.4 degrees
-----------------------------------
From (1),
v = SQRT[2hg/sin2]
Substituting values,
v = SQRT[(2*26.8*9.8) / sin2(54.4)]
= 28.2 m/s
So, the correct answer is A) 28.2 m/s, 54.4 degrees above horizontal