# NCERT Class 9 Science Solutions: Chapter 10 – Gravitation Part 7

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Question 14:

Q. A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity just before touching the ground.

Answer:

According to the equation of motion under gravity:

Where,

Initial velocity of the stone

Final velocity of the stone

Height of the stone

Acceleration due to gravity

Hence, the velocity of the stone just before touching the ground is

Question 15:

Q. A stone is thrown vertically upward with an initial velocity of 40 taking, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?

Answer:

According to the equation of motion under gravity:

Where,

Initial velocity of the stone

Final velocity of the stone

Height of the stone

Acceleration due to gravity

Let be the maximum height attained by the stone.

Therefore,

Therefore, total distance covered by the stone during its upward and downward journey

Net displacement of the stone during its upward and downward journey