Question

A stone is released from the top of a tower of height 45m. The final velocity of the stone just before touching the ground will be (take g = 10 m/s² )Required to answer. Single choice.

(1 Point)

30 m/s

196 m/s

60 m/s

40 m/s​

Answer 1

Answer:

• 30m/s is the required velocity.

Explanation:

Given:-

• Initial velocity ,u = 0m/s
• Height ,h = 45 m
• Acceleration due to gravity ,g = 10m/s²

To Find:-

• Final Velocity before touching the ground ,v

Solution:-

As we have to calculate the Final velocity of ball before touching the ground.

Using 3rd Equation of Motion

• v² = u² +2gh

where,

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

Substitute the value we get

→ v² = 0² + 2×10 × 45

→ v² = 0 + 20 × 45

→ v² = 900

→ v = √900

→ v = 30 m/s

• Hence, the velocity of ball before touching the ground is 30 m/s.

Hence, the required option is 1) 30 m/s.

Answer 2

Answer:

Given :-

• Height = 45 m
• Initial Velocity = 0 m/s
• Acceleration = 10 m/s

To Find :-

Final velocity

Solution :-

According to third equation of motion

v² = u² + 2gh

v² = 0² + 2(10)(45)

v² = 0 + 20 × 45

v² = 0 + 900

v² = 900

v = √900

v = 30 m/s

Hence :-

Option A