Question

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Answer (Detailed Solution Below)

Option 3 : $4\,\text{s}$ / $4\,\text{से}$

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Detailed Solution

सही उत्तर $4\,\text{s}$ / $4\,\text{से}$ है।

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Question:

A stone is dropped from rest from a height of $80\,\text{m}$. Taking $g = 10\,\text{m/s}^2$ and neglecting air resistance, how long does it take to reach the ground? / एक पत्थर विरामावस्था से $80\,\text{मी}$ की ऊँचाई से गिराया जाता है। $g = 10\,\text{मी/से}^2$ मानते हुए और वायु प्रतिरोध नगण्य मानते हुए, इसे धरती तक पहुँचने में कितना समय लगेगा?

1.
$8\,\text{s}$ / $8\,\text{से}$
2.
$5.66\,\text{s}$ / $5.66\,\text{से}$
3.
$4\,\text{s}$ / $4\,\text{से}$
4.
$16\,\text{s}$ / $16\,\text{से}$

Correct Answer: $4\,\text{s}$ / $4\,\text{से}$

From $h = \frac{1}{2}gt^2$, $t = \sqrt{2h/g} = \sqrt{160/10} = 4\,\text{s}$. / $h = \frac{1}{2}gt^2$ से, $t = \sqrt{2h/g} = \sqrt{160/10} = 4\,\text{से}$।

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