# NCERT Class 9 Science Solutions: Chapter 10 – Gravitation Part 5

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Question 8:

Q. What is the acceleration of free fall?

Answer:

When objects fall towards the Earth under the effect of gravitational force alone, then they are said to be in free fall. Acceleration of free fall is 9.8, which is constant for all objects( irrespective of their masses).

Question 9:

Q. What do we call the gravitational force between the earth and an object?

Answer:

Gravitational force between the earth and an object is known as the weight of the object.

Question 10:

Q. Amit buys few grams of gold at the poles as per the instruction of one of his friends. He hands over the same when he meets him at the equator. Will the friend agree with the weight of gold bought? If not, why? [Hint: The value of is greater at the poles than at the equator].

**Answer:**

Weight of a body on the Earth is given by:

Where,

Mass of the body

Acceleration due to gravity

The value of is greater at poles than at the equator. Therefore, gold at the equator weights less than at the poles. Hence, Amit’s friend will not agree with the weight of the gold bought.

Question 11:

Q. Why will a sheet of paper fall slower than one that is crumpled into a ball?

**Answer:**

When a sheet of paper is crumpled into a ball, then its density increases. Hence, resistance to its motion through the air decreases and it falls faster than the sheet of paper.