The following questions are for a quick revision of the chapter “Gravitation” for CBSE Class 9. There are many other questions which can be asked from the portion allotted for SA1, but will mainly based on these concepts. The questions are based on the bare essential concepts; the minimum level of learning expected from the children

**State the universal law of gravitation.**

Universal law of gravitation states that every object in the universe attracts every other object with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them**Define G. Write its value with proper units of SI**

G is the universal constant of gravitation. It is defined as the gravitational force of attraction between two objects of mass 1 kg each separated by a distance of 1m. Its value is 6.67 x 10^{-11}Nm^{2}kg^{-2}- What is the difference between gravity and gravitation?

The force of gravitation exerted by earth (or any other planet) on the objects on its surface is called gravity. Every object attracts every other object due to the force of gravitation. So, Gravity is a special case of Gravitation - Define acceleration due to gravity.
- Why the moon is not “falling” to earth?
- Derive an expression for the acceleration due to gravity.
- Write the differences between g and G.
- calculate the value of g on the surface of earth.
- Discuss the variation of g with height, depth and latitude.
- Distinguish mass and weight.