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Motion In Straight Line

Question

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How will you ‘weigh the sun’, that is estimate its mass? The mean orbital radius of the earth around the sun is 1.5 × 10⁸ km.

Solution

Orbital radius of the Earth around the Sun, r = 1.5 × 10¹¹ m
Time taken by the Earth to complete one revolution around the Sun,
T = 1 year
= 365.25 days
= 365.25 × 24 × 60 × 60 s
Universal gravitational constant, G = 6.67 × 10^–11 Nm² kg^–2
Thus, mass of the Sun can be calculated using the relation,
M =

fraction numerator 4 straight pi squared straight r cubed over denominator GT squared end fraction

=

fraction numerator 4 space straight x space 3.14 squared space straight x space left parenthesis 1.5 space straight x space 10 to the power of 11 right parenthesis cubed over denominator left square bracket 6.67 space straight x space 10 to the power of negative 11 end exponent space straight x space left parenthesis 365.25 space straight x space 24 space straight x 60 space straight x 60 right parenthesis squared right square bracket end fraction

= 2 × 10³⁰ kg
Hence, the mass of the Sun is 2 × 10³⁰ kg.

Some More Questions From Motion in Straight Line Chapter

Is absolute rest or absolute motion possible?

What is the most essential thing to study the motion of a body?

Can a body be always at rest in some frame?

Can a body be in motion in the frame associated with the body itself?

When an object in motion can be considered as particle or point object?

Can you think of physical phenomena involving the moon in which moon cannot be treated as particle?

A train is crossing the bridge. Can it be taken as a particle?

Can a train be taken a particle? Give an example in support of your answer.

A particle is moving along curved line in space. Is the motion one dimensional?

State which of the following are examples of one, two or three dimensional motion:

(a) A kite flying in the sky.

(b) The earth revolving around the sun.

(c) A train moving along the equator of the earth in clockwise direction.

(d) Accelerated motion of a particle in a straight line.

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