Question

a body projected vertically upward reaches a height of 89 m. calculate it's intial velocity?​

Answer 1

▶ Solution :

Given :

▪ Maximum height achieved by ball = 89m

To Find :

▪ Initial velocity of projection.

Concept :

✒ Here gravitational acceleration is constant throughout the motion.

✒ So, we can apply equation of kinematics directly.

✒ Third equation of kinematics is given by

☞ v^2 - u^2 = 2gH

• v denotes final velocity
• u denotes initial velocity
• g denotes gravitational acceleration
• H denotes maximum height

Calculation :

→ v^2 - u^2 = 2(-g)H

Negative sign shows opposite direction

→ (0)^2 - u^2 = -2(10)(89)

→ u^2 = 1780

→ u = √(1780)

→ u = 42.19mps

Answer 2

Given ,

• Displacement of body (s) = -89 m , because the body is projected vertically upward

• Final velocity (v) = 0 m/s

We know that , the third equation of motion is given by

(v)² - (u)² = 2as

Thus ,

➡(0)² - (u) ² = 2 × 10 × -89

➡-(u)² = -1780

➡u = √(1780)

➡u = 41.19 m/s

Hence , the initial velocity of body is 41.19 m/s