Question

An object is peojected upwords with a velocity of 100 m/s. It will strike the ground after 10 sec or 20 sec or 15 sec or 5 sec plizzz tell me guy's?​

Answer 1

Answer:

20 sec.

Explanation:

Given :

Initial velocity ( u ) = 100 m / sec

Final velocity ( v ) = 0 m / sec

We have equation of motion due to gravity for upward

v = u - g t

where

v = Final velocity

u = Initial velocity

g = acceleration due to gravity

t = time

Put the value here we get

0 = 100 - g × t

Put value of g  = 10 here

100 t = 100

t = 10 sec.

It is time for ascent

We know time of ascent is equal to time descent.

So total time = 2 × 10 = 20 sec.

Thus we get answer.

Another method of solving this question :

Time of flight = 2 u sin theta / g

when body is going upward it will make angle 90

Time of flight = 2 u sin 90 / g

sin 90 = 1

Time of flight = 2 u * 1 / g

Tme of flight = 2 u / g

Put u = 100 and g = 10 here

Time of flight = 2 * 100 / 10

Time of flight = 2 * 10 = 20 sec.