Question

A 5 kg stone falls from a height of 100m and penetrates 2m layer of sand.The time of penetration is:
i) 14.285 sec.
ii)0.089 sec.
iii)7.14 sec.
iv)0.89 sec.​

Answer 1

Answer:

the time of penetration is 0.89 second

Answer 2

Answer:

(B)

Step-by-step explanation:

Speed of the stone just before touching the sand is is

v=√2gh=√2×9.81×1000=140.07m's

Declaration of the stone due to sand is

v²- u²=-2 as

0-140.07²=-2(a)(2)

a=4905m/s²

we have initial speed and the declaration, from

v=u-at

u=at

t=u÷a =140.07÷4905=0.0285s

So, the answer is 0.089sec.

HOPE IT HELPS YOU