Question

A body is dropped from a certain height and acquired a speed of 20ms-1
when reaches the ground .find height

Answer 1

Given:

Body is dropped from certain height and its final velocity = 20 m/s. The word dropped signifies zero initial velocity.

To find:

Height from which it was dropped

Calculation:

Since the acceleration due to gravity is considered to be constant whole throughout the journey, we can easily apply equation of kinematics:

${v}^{2} = {u}^{2} + 2gh$

$= > {(20)}^{2} = {(0)}^{2} +( 2 \times 10 \times h)$

$= > h = \dfrac{ {(20)}^{2} }{20}$

$= > h = 20 \: m$

So the height from which the object was released is 20 m

Answer 2

Aɴꜱᴡᴇʀ

✭ So the height from which the ball was thrown is 20 m

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Gɪᴠᴇɴ

➤ When a body was dropped from a certain height then the speed acquire by it is 20 m/s

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ᴛᴏ ꜰɪɴᴅ

➜ The height from which the body falls from

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Sᴛᴇᴘꜱ

Here we can use value of g(acceleration due to gravitation) as 10m/s² just to make the calculation easy

❍ So here we may use the formula v² - u² =2as

Where,

➠ v = final velocity

➠ u = initial velocity

➠ a = acceleration

➠ s = distance(here hight)

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☞ So substituting the given values,

$\tt \dashrightarrow {20}^{2} - {0}^{2} = 2 \times 10 \times s \\ \\ \tt \dashrightarrow400 = 20s \\ \\ \tt \dashrightarrow s = \cancel \frac{400}{20} \\ \\ \tt \pink{ \dashrightarrow{}s = 20 \sf{}m}$

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