Chapter 7

Question 1

Newton’s universal law of Gravitation

Answer 1

Every particle in the universe attracts every other particle with a force that is perpendicular to the product of their masses and inversely proportional to the square of the distance between them

f proportional to m1 m2
f inversely proportional to r^2

therefore; F=G* (m1/m2/r^2)

Question 2

Universal Gas Constant

Answer 2

it is the force of attraction between two bodies of unit mass and unit distance between them.

G= (Fr^2)/ (m1m2)
Si Unit: Nm^2kg^-2
Dimensional formula: M^-1L^3T^-2

Question 3

Relation between g and G

Question 4

variation of g with altitude

Question 5

variation og g with depth

Question 6

gravitational potential energy

Question 7

gravitational potential energy

Question 8

gravitational potential

Question 9

escape velocity

Question 10

orbital velocity

Question 11

kepler’s laws

Answer 11

1. Law of Orbits:
   each planet revolves around the sun in an elliptical orbit with the sun situated at one of the two foci.
2. Law of areas:
   the radius vector from the sun to a planet sweeps out equal areas in equal intervals of time, arial velocity of a planet around the sun is constant.
3. Law of periods :
   the square of the period of revolution of a planet around the sun is proportional to the cube of semi- major axis of its elliptical orbit.
   T^2 = kR^3