An object is projected for the height of 80 m above the ground with a velocity of 40ms−¹ at the angle of 30° to the horizontal. The time of flight?

A. 8 s
B. 4 s
C. 16 s
D. 10 s

Correct Answer:

Option B – 4 s

Explanation

For a body projected at an angle θ to the horizontal, the time of the flight is given by T = (2u sin θ)/g =(2x 40)x sin (30)/10 =(2 x 40) x (0.5)/10 = 4.0secs.