Question

A body is allowed to fall freely from a building of height 20 metre with what velocity ball strikes ground *
A 10 m/s
B 20 m/s
C 40m/s
D 5m/s
no wrong answer needed​

Answer 1

Answer:

• Option (B) 20m/s is the required velocity.

Explanation:

According to the Question

It is given that,

• Height of building ,h = 20m
• Initial velocity ,u = 0m/s
• Acceleration due to gravity ,g = 10m/s²

we have to calculate the velocity of ball strikes the ground .

So we apply here the kinematics equation.

• v² = u² + 2gh

by putting the value we get

➻ v² = 0² + 2×10×20

➻ v² = 0 + 20×20

➻ v² = 400

➻ v = √400

➻ v = 20m/s

• Hence, the velocity of ball strikes the ground is 20m/s.

So, the required option is (B) 20m/s.

Answer 2

⇝Appropriate Question :

A body is allowed to fall freely from a building of height 20 metre with what velocity ball strikes ground ( taking g = 10 m/s).

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⇝Given :-

• ➵ A body falls freely from a height of 20 .
• ➵ G = 10 m/s.

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⇝To Find :-

• ➵ With what velocity it will hit the ground ?

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⇝Solution :-

❒ We know that :

${\large{\red{\bigstar \: \: \: \: \: {\blue{\underbrace{\underline{\orange{\bf{V² = U² + 2gh}}}}}}}}}$

✏ Here :

• ➳ V = Velocity with ball will hit the ground = ?
• ➳ U = Initial Velocity = 0m/s
• ➳ G = Force due to gravitation = 10 m/s
• ➳ H = Height = 20 m

❒ Velocity when ball hits the ground :

${\large{\longmapsto{\bf{V² = U² + 2gh}}}}$

${\large{\longmapsto{\bf{V² = 0² + 2 \times 10 \times 20}}}}$

${\large{\longmapsto{\bf{V² = 0 + 20 \times 20}}}}$

${\large{\longmapsto{\bf{V² = 0 + 400}}}}$

${\large{\longmapsto{\bf{V² = 400}}}}$

${\large{\longmapsto{\bf{V = \sqrt{400} }}}}$

${\large{\green{:{\longmapsto{\red{\overline{\underline{\boxed{\bf{V = 20 m/s}}}}}}}}}}$

❒ Hence :

➤ Ball will hit with the velocity of 20 m/s.

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