1.

if an object is projected under gravity but in air resistance then which time will be greater ? upward journey time or downward journey time?

Answer»

Answer:

Explanation:

TIME of Ascent:

The time taken by body thrown up to reach maximum height H is called as time of ascent.

Let t₁ be time of ascent.

at maximim height, its velocity is zero, V=0

hence, V=u-gt

O=u-gt₁

t1=u/g

(1)

Time of descent:

after reaching the maximum height, the body begins to travel downwards and reaches the ground.

The time taken to by a freely falling body to touch the ground is called time of descent.

Initial velocity for downward JOURNEY is zero u= 0

let t₂ be time of descent.

Initial velocity for downward journey is zero 9 u= 0

let t₂ be time of descent.

s=ut+1/2 gt²

h=0+1/2gt₂²

t2=√2h/g

but, h=u²/2g

so, we get

t₂=√2u²/2g

65

--(2)

from equation 1 and 2 we can say

the time of ascent is equal to time descent in the CASE of bodies moving under gravity.


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