An object is projected with a velocity of 50ms-1 from ground level at an angle \theta to the vertical. If the total time of flight of the projectile is 5s, what is the value of \theta? (g = 10ms-2)
A
0°
B
30°
C
45°
D
60°
E
90°
Verified Correct Answer: D.
Physical Principles & Numerical Solution
Time of flight =\( \frac{2Usin\theta}{g}\)
T = 5, g = 10m/s2
\(5 = \frac {2\times 50sin\theta}{10}\)
\(sin\theta =\frac {50}{100}\)
\(\theta = 30\)
vertical angle = 90 - 30 = 60^\circ
Source: Myschool Past Questions Archive (Record #42884)