two bodies are thrown vertically upwards from walls of height 2.2 m and 1.05m respectively, with an initial velocity of 10 m/s. the ratio of their times of flight is (g=10m/s2)
a.22/21 b. 12/11 c. 44/23 d. 13/11
For the body projected from a wall of height 2.2 m, initial velocity, u = 10 m/s
Displacement, s = - 2.2 m [downward]
Acceleration, a = -10 m/s2 [downward]
Using, s = ut + ½ at2
=> -2.2 = 10t + (0.5)(-10)(t2)
=> 5t2 -10t -2.2 = 0
=> t1 = 2.2 s
For the body projected from a wall of height 1.05 m, initial velocity, u = 10 m/s
Displacement, s = - 1.05 m [downward]
Acceleration, a = -10 m/s2 [downward]
Using, s = ut + ½ at2
=> -1.05 = 10t + (0.5)(-10)(t2)
=> 5t2 -10t -1.05 = 0
=> t2 = 2.1 s
So, required ratio is, t1 : t2 = 2.2 : 2.1 = 22 : 21