Question

answer this please and why we use third equation of motion.​

Answer 1

Answer:

• The maximum height (H) attained will be u² / 2 g.

Given:

1. Initial velocity = u
2. Maximum height attained = H

Explanation:

$\rule{300}{1.5}$

From third Kinematic Equation we know,

⇒ v² - u² = 2 a s

Where,

• v Denotes Final velocity.
• u Denotes Initial velocity.
• a Denotes acceleration.
• s Denotes distance.

⇒ v² - u² = 2 a s

At Highest position the Final velocity (v) will be zero.

And acceleration due to gravity will be taken as negative because the body moves against the Force of Gravity.

Substituting the values,

⇒ (0)² - (u)² = 2 × - g × H

⇒ 0 - u² = - 2 g H

⇒ - u² = - 2 g H

⇒ u² = 2 g H

⇒ H = u² / 2 g

⇒ H = u² / 2 g m.

∴ The maximum height (H) attained will be u² / 2 g.

$\rule{300}{1.5}$

$\rule{300}{1.5}$

Answer 2

Question :

In Picture Above

Solution :

By Equation of motion ,

${v}^{2} = {u}^{2} + 2as \\ \\ {0}^{2} = {u}^{2} - 2 \: g \: h \\ \\ h \: = \dfrac{ {u}^{2} }{2g}$