Page 2 - Simplied Force

SIMPLIFIED COURSE ON SEE SCIENCE : CHAPTER- FORCE

Class: TEN
Subject: SCIENCE

FORCE

Force [ Old French: force-"physical strength"]

• Push or pull acting upon an object as a result of its interaction with another object.
• An external agency that changes or tends to change the position of a body

Two Broad Types:

Contact Forces (Touching two surfaces) Action-at-a-Distance Forces (no touch at all)

Frictional Force Gravitational Force
Tension Force Electrical Force
Normal Force Magnetic Force
Air Resistance Force
Applied Force
Spring Force

Models of the universe

Geocentric model [Ptolemaic Model] (Gr: Geo- Earth, Centric-at the Center)

The astronomical model in which the Earth lies in the Center and all the other planets, the Moon and
the Sun revolve around the Earth is called Geocentric model. Under this model, the Sun, Moon, stars,
and planets all orbited Earth.
After being an important model of the universe for about 1000 years, various other scientists
discovered new ideas and ultimately heliocentric model was proposed.

Heliocentric model [Copernican Model] (Gr: Helios- Sun, Centric-at the Center)

The astronomical model in which the Earth and planets revolve around the Sun at the center of the
Solar System.

• Coincides with the Solar system Model

-Refined by Kepler and Newton to explain the phenomenon. The heliocentric models and the Kepler's
laws reveal the path for Isaac Newton to establish the Newtons law of gravitation.
Gravity (Latin gravitas ; weight')

The force of attraction between any two bodies in this universe due to the virtue of their masses.

• The universal force of attraction acting between all matter.
• Anything that has mass has gravity. Objects with more mass have more gravity.
• Gravity also gets weaker with distance.

Shiva Mainali www.shivamainali.com.np shiva@shivamainali.com.np