plz explain the difference btw inertial and gravitatational mass.If these 2 are equal,why did we define 2 kinds of mass?plz help

inertial mass is the basic property of the material and it does not change with time and place however the gravitational mass, which is the also known as weight, gets affected by the value of "g", the gravitational acceleration, which is different for different planets.it is therefore that the inertial mass of a man will be same on earth and moon but the gravitational mass shall be different as the value of 'g' is different for these two celestial bodies (the value of 'g' depends upon the mass of the body ). to be very precise the gravitational mass = g times the inertial mass )

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