Page 4 - Simplied Force

SIMPLIFIED COURSE ON SEE SCIENCE : CHAPTER- FORCE

Acceleration due to gravity
Acceleration due to gravity is defined as the acceleration produced in a freely falling body due to the
force of gravity of the earth towards its center. It is denoted by g and its average value is 9.8 m/s .
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Variation in the value of g
i. Variation due to shape [ On the surface]
ii. Variation with height
iii. Variation with depth

Gravitational field
The space around a mass over which it can exert gravitational force on other masses is called the
gravitational field of the mass.

Mass
The amount of substance contained in a body is called the mass. The mass of the body is measured by
using a physical balance or beam balance. It unit if kg in SI. The mass of the body is dependent upon
the number of atoms and average mass of atoms present in the body.
Weight
The weight of a body is defined as the force with which it is attracted towards the center of the earth. SI
unit of weight is Newton (N). Its value changes from place to place as it depends on the acceleration
due to gravity (g). It is a vector quantity

Weightlessness
The weightlessness of a body is the state in which the body experiences that the body is not being
attracted by any force

Freefall
If a body is falling freely under the action of gravity alone neglecting air resistance, the motion is called
freefall

Motion under gravity

When a body is released from a height, it travels vertically downward towards the surface of earth due to
the force of gravitational attraction exerted on body by the earth. This motion is termed as motion under
gravity.

➢ The movement of an object whose vertical motion is affected by the presence of gravity.

Coin and Feather Experiment

• Gravity causes uniform acceleration

• In his Book called New Sciences, Galileo proposes that heavy bodies actually fall in just that way
and that if it was possible to create a vacuum, any two falling bodies would travel the same
distance in the same time.
• Experimental evidence was given by Robert Boyle in his Tube Experiment

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