Page 10 - Simplied Force

SIMPLIFIED COURSE ON SEE SCIENCE : CHAPTER- FORCE

7) Why does a sheet of paper fall later on the earth surface than that the paper ball of equal weight
if thrown from a certain height?

Ans: A sheet of paper fall later on the earth surface than that the paper ball of equal weight if thrown from
a certain height because the sheet of the paper experiences a larger air resistance due to its larger surface
area but the paper ball has less surface area so that air interferes less on paper ball than that of paper sheet.
8) What are the two factors that affect the force of gravitation?

Ans: The two factors that affect the force of gravitation are:-

a) Product of masses of any two bodies and

b) Square of the distance between their centers

9) The weight of the object is more at polar region than equatorial region, why?

Ans: The weight of the body depends upon the acceleration due to gravity (g) and the value of'g' is
2
inversely proportional to square of the radius of the earth (i.e. g 1/R ). The polar radius of the earth is
less than the equatorial radius as the earth is not a perfect square. Hence, the weight of the body is more
at the polar region than at the equatorial region.

10) When a person jumps from the Aeroplane with parachute can land safely on the earth surface
but it is not possible on the moon, why?

Ans: When a person jumps from the aeroplane with a parachute, he can safelv on the earth surface because
on the earth there are layers of different gases. When a parachutist jumps out of the aeroplane, parachute
opens and expands due to which air exert large resistance on the parachute so that parachute falls down
slowly and uniformly. But it is not possible on the moon because there is the absence of atmosphere on
the moon. So, upthrust of air is not acted on parachute and falls with acceleration equal to acceleration
due to gravity.

11) What is free fall and weightlessness?

Ans: When a body is falling freely towards the Centre of the earth under the influence of the gravitational
pull of the earth without any external resistance, the fall of the body is called free- fall.
Weightlessness of a body is the state in which the body feels that it is not being attracted by any force.

12) Why satellites not fall while revolvin g around Earth?

Ans: Satellites do not fall while revolving around sun due to the balance of two factors:

a) The gravitational pull between the Earth and the satellite i.e. centripetal force.

b) Velocity or the speed at which it would travel in a straight line i.e. centrifugal force.

13) What effect will be on acceleration due to gravity if radius of the earth is decreased?

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