Question

A body falls from a height of 100. . After 2 seconds if gravity disappears, find the total time it would take to reach the ground.​

Answer 1

Answer:

4 sec

Explanation:

distance travelled in  2 sec

s=ut+1/2 $at^{2}$

u=0

a=g=10m/sec square

therefore

s=$0+\frac{1}{2} *10*2^{2}$

= 20

remain

100-20=80

v=u+gt

v=0+10*2

=20m/s

time taken=80/20

=4 sec

Answer 2

Explanation:

Here, A body falls from a height of 100. . After 2 seconds if gravity disappears...

so, initial velocity, u = 0 m/s

then, final velocity, v = u+ at. ,a = gravitational force...

$or \: \: v = 0 + 10 \times 2$

$or \: \: v = 20m {s}^{ - }$

Now, as after 2s gravity disappears

so, the velocity becomes constant.

or, v = 20 m/s...

therefore, total distance travel in 2s...

$s = ut \: + \frac{1}{2} a {t}^{2}$

$or \: \: s = 0 + 10 \times {2}^{2} \times \frac{1}{2}$

$or \: \: s = 20m$

so, the

remaining height is

$= 100 - 20$

$= 80m$

then,

$80 = 20 \times t \: + \frac{1}{2} \times 0 \times {t}^{2}$

$or \: \: 20t = 80$

$or \: \: t = 4s$

so, the total time it would take to reach the ground is (4+2)=6second..

thanks a lot...