Question

find the time taken by the body projected vertically up with a speed of u ,to return back to the ground

Answer 1

Answer:

There is a formula to find the time taken by the body to return to its initial position after thrown vertically upward .

It is given as ,

t = 2u / g

This formula is derived in the following manner ,

When thrown vertically upward :

u = u

a = -g

v = 0

t = v-u / a

 = -u / -g

 = u/g

When falling freely ,

u = 0

a = g

v = u + at

  = gt

t = v/g

Since the body reaches the initial point with the same velocity as it was thrown with ,

v = u

t = u/g

total time taken = u/g + u/g

                          = 2u / g

Hope it helps :)

Answer 2

The given question is about Physics.

Formula = 2u/g

( derivation of the formula)

where,  

           u = initial velocity

           v = final velocity

           a = acceleration due to gravity

    so,  a = -g

    now, time taken needs to be find

            t = v-u/a

            v = 0

        ∴  t = -u/-g

Now, the minus signs get canceled and the equation becomes,

            t = u/g

Now suppose the object goes up at a speed of u meter/sec, it will also fall at the same speed.

         ∴ t = 2u/g

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