Hindi
Study the definition of pronoun and underline
the pronouns written in Hindi notebook for a review on Thursday, 10/3/16.
Science
Read
the following content and answer the questions that follow in your science note
book and submit the same on 10-3-16.
The Earth revolves around the sun in an elliptical orbit. The moon
orbits the Earth in the same way. But what keeps the Earth and the moon in orbit? Why don’t they
just fly off into space? Or crash into each other?
The first person to answer these questions was the scientist Isaac
Newton. Newton realized that there must be a force acting between Earth and the
moon that kept the moon in orbit.
Newton’s Laws of Motion
First Law:
Objects tend to stay at rest or
move in a straight line at a constant speed unless acted upon by an outside
force.
Newton’s first law of motion is, essentially, the definition of
inertia—the tendency of an object to resist a change in motion. The more mass
an object has, the greater its inertia. An object with greater inertia is more
difficult to start or stop. Examples to explain to the students how Newton's
first law occurs in everyday events:
a) Car suddenly stops and you strain against the seat belt
b) When riding a horse, the horse suddenly stops and you fly over
its head
c) The magician pulls the tablecloth out from a table full of
dishes
d) The difficulty of pushing a dead car
e) Car turns left and you appear to slide to the right
Second Law
The force acting on a body is
directly proportional to, and in the same direction as, its acceleration.
Newton’s second law tells us that the force (F) on an object is
directly proportional to its acceleration(a), and that is dependent on its mass(m).
So, the second law can be summed up as
F =
ma.
Acceleration depends on the objects mass and on the net force
acting on the object.
Newton’s Law of Universal Gravitation
Isaac Newton also developed the theory that explains why
satellites stay in orbit. Newton’s law of universal gravitation describes how every object
in the universe is attracted to every other object. The same gravity that makes an
apple fall to the ground and keeps a person from floating away into the sky,
also holds the Moon in orbit around Earth, and Earth in its orbit around the
Sun.
Orbital Motion
Newton concluded that two factors: inertia and gravity combine to
keep the Earth in orbit around the sun and the moon in orbit around the earth. The
Earth’s gravity keeps pulling the moon toward it, preventing the moon from moving
in a straight line. At the same time, the moon keeps moving forward because of inertia.
If not for Earth’s gravity, the moon would shoot off into space in a straight
line,and if not for the moon’s inertia, the moon would collide with Earth due
to the pull of Earth’s gravity.
Third Law
To every action, there is an
equal and opposite reaction.
Examples related to the third law. They can be listed as follows:
a) Guns being fired
b) Two cars hit head on
c) Firemen pouring out water through a fire hose.
d) Jumping out of a boat onto the dock
Q.1. Write Newton’s three
laws with an example.
