Question

if a body dropped from the height of 245 metre what is the velocity of the body after 2 second also find the velocity of the body just before touching the ground​

Answer 1

1. Velocity after 2 seconds

Given:

• Height (h) = 245 m

• Time (t) = 2 seconds

To calculate:

• Velocity after 2 seconds (v)

Calculation:

By using the first equation of motion for frèély falling bodies,

$\bigstar \: \boxed{\sf {v = u + gt}}$

Where,

• v denotes final velocity.
• u denotes initial velocity.
• g denotes acceleration due to gravity.
• t denotes time.

1. Value of g = 10 m/s²
2. Initial velocity (u) = 0 , whenever the body is thrown vertically downwards ; its initial velocity is 0.

Substituting values,

$\longrightarrow$ v = 0 + ( 10 × 2 ) m/s

$\longrightarrow$ v = 0 + 20 m/s

$\longrightarrow$ v = 20 m/s

Therefore, the velocity of the body after 2 second is 20 m/s.

2. velocity of the body just before touching the ground

Given:

• Height (h) = 245 m

• Initial velocity (u) = 0

• Acceleration due to gravity (g) = 10 m/s²

To calculate:

• velocity of the body just before touching the ground (v)

Calculation:

By using the third equation of motion for frèély falling bodies,

$\bigstar \: \boxed{\sf { {v}^{2} = {u}^{2} + 2gh}}$

• v denotes final velocity.
• u denotes initial velocity.
• g denotes acceleration due to gravity.
• h denotes height.

$\longrightarrow$ v² = 0² + ( 2 × 10 × 245 ) m/s

$\longrightarrow$ v² = 0 + ( 20 × 245 ) m/s

$\longrightarrow$ v² = 0 + 4900 m/s

$\longrightarrow$ v = √4900 m/s

$\longrightarrow$ v = 70 m/s

Therefore, velocity of the body just before touching the ground is 70 m/s.

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More Information:

Equations of motion ( for frèély falling bodies) :

1. v = u + gt

2. h = ut + ½gt²

3. v² = u² + 2gh

Where,

• v denotes final velocity.
• u denotes initial velocity.
• g denotes acceleration due to gravity.
• t denotes time.
• h denotes height.

Note :

• When the body is thrown vertically upward, then g= –10m/s².
• When the body is thrown vertically downwards, then g= 10m/s².