Question

An object thrown vertically upwards is at the same height at times 2 s and 8 s. The total time for which it stays in air and magnitude of its initial velocity respectively are [Take g = 10 m/s2] (1) 10 s, 100 m/s (2) 10 s, 50 m/s (3) 5 s, 100 m/s (4) 5 s, 50 m/s

Answer 1

Answer:

Option (2) 10 s , 50 m / s

Explanation:

T = t1 + t2

where according to the question t1 = 2 s , t2 = 8 s

total time = 8+2 = 10s ⇒ T

T = 2u/g

u = T × g / 2  

  = 10 × 10 / 2

  = 100 / 2

   =  50 m/s

Hope this will help you in some or the other way.