Question

A ball is projected vertically upward with an initial velocity of 50 ms^-1 at t = 0s, At t = 2s, another ball is projected vertically upward with same velocity. At t = ______ s, second ball will meet the first ball (g = 10 ms^-2).

विकल्प

• 3

• 6

• 9

• 11

Answer 1

A ball is projected vertically upward with an initial velocity of 50 ms^-1 at t = 0s. At t = 2s. another ball is projected vertically upward with same velocity. At t = 6 s, second ball will meet the first ball (g = 10 ms^-2).

Explanation:

Let the two ball meet at t = t sec.

Then, first ball get 't' see and second ball get ( t - 2) sec and they will meet at same height. 

So, h₁ = h₂

⇒ `50"t" -1/2"gt"^2=50("t"-2)-1/2"g"("t"-2)^2`

⇒ `0 = -100+1/2"g"["t"^2-("t"-2)^2] `

⇒ 20 = 4t - 4

⇒ 24 = 4t 

⇒ t = 6 sec.