+91-8076753736 [email protected]

-->

Motion In Straight Line

Question

Wired Faculty App

Suppose there existed a planet that went around the sun twice as fast as the earth.What would be its orbital size as compared to that of the earth?

Solution

Time taken by the Earth to complete one revolution around the Sun,
T_e = 1 year
Orbital radius of the Earth in its orbit, R_e= 1 AU
Time taken by the planet to complete one revolution around the Sun, T_P = ½T_e
= ½ year
Orbital radius of the planet = R_p
From Kepler’s third law of planetary motion,

open parentheses straight R subscript straight P over straight R subscript straight e close parentheses cubed space equals space open parentheses T subscript P over T subscript e close parentheses squared space open parentheses straight R subscript straight P over straight R subscript straight e close parentheses space equals space space open parentheses T subscript P over T subscript e close parentheses to the power of begin inline style bevelled 2 over 3 end style end exponent space space space space space space space space space space space space space space equals space open parentheses fraction numerator bevelled 1 half over denominator 1 end fraction close parentheses to the power of begin inline style bevelled 2 over 3 end style end exponent space space space space space space space space space space space space space space equals open parentheses space 0.5 close parentheses to the power of begin inline style bevelled 2 over 3 end style end exponent space space space space space space space space space space space space space space equals 0.63 space

Hence, the orbital radius of the planet will be 0.63 times smaller than that of the Earth.

Some More Questions From Motion in Straight Line Chapter

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.

Define distance.

Define displacement.

Can magnitude of displacement be greater than distance travelled by particle?

Mock Test Series

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation