Which of the following are true?
The centre of mass of an extended body on the surface of the earth and its centre of gravity
Molecules in air in the atmosphere are attracted by gravitational force of the earth. Explain why all of them do not fall into the earth just like an apple falling from a tree.
Air molecules in the atmosphere are attracted vertically downward by gravitational force of the earth just like an apple falling from a tree. Air molecules move randomly due to their thermal velocity and hence the resultant motion of air molecules is not exactly in the vertical downward direction.
But in case of apple, only vertical motion dominates because of being heavier than air molecules. But due to gravity, the density of atmosphere increases near to the earth's surface.
Give one example each of central force and non-central force.
Example of central force Gravitational force, electrostatic force etc.
Example of non-central force Nuclear force, magnetic force acting between two current carrying loops etc.
Draw areal velocity versus time graph for mars.
Areal velocity of a planet revolving around the sun is constant with time. Therefore, graph between areal velocity and time is a straight line (AB) parallel to time axis. (Kepler's second law).
