Gravitational force

1. Mass and gravity   

2. Magnitude  and     direction      of gravitational force

3. Gravitational force between two masses-phet     

4. Gravitational forces among three masses in a plane     

5. Geometrical approach

1. Balance is measuring the heavy mass - not the weight or inertia mass.

2. A scale is measuring the weight or  apparent weight.

12.3  *Some aspects of gravity: 

3. Inertial mass is defined as the constant of proportionality b/w the applied force and the acquired acceleration (the applied force must not be the gravitational force)    Ratio of two inertial masses    Units

4. Weight is gravitational force    Measurement of the weight by tension or compression

5. 
   

6. Measurement of the ratio of two weights by balance ( torque and distances)

7. Weight and  heavy mass (gravitational mass)

8. It is experimental  observation that for any two bodies the ratio of their inertial masses is equal to the ratio of their weights. This observation is elevated by Einstein to a principle. The Equivalence Principle states that the ratio of the inertial mass to the heavy mass is the same for every particle. 

9. Variation of the weight with the altitude.

10. Apparent weight ( weight in non-inertial systems)