Q10 of 33 Page 63

Find the ratio of the magnitude of the electric force to the gravitational force acting between two protons.

Coulomb’s force of repulsion between two protons is given by –



Where,


q1 and q2 = are the charges


k = proportionality constant = 9×109


r= distance between the charges


Now, gravitational force,



Where,


G = universal gravitation constant =


m1 =mass of first object


m2 = mass of second object


r = distance between the objects


Now, we know that-


Charge of the proton, q = 1.6×10-19 C


Mass of the proton = 1.67×10-27 kg


Let r be the distance between two protons



Coulomb force of repulsion between the two protons is given by –



fe=14π∈0×q2r2=9×109× (1.6)2×10-38r2


Gravitational force between the protons is given by –



Dividing the equations -




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The force with which the earth attracts an object is called the weight of the object. Calculate the weight of the moon from the following data: The universal constant of gravitation G = 6.67 × 10–11 N–m2/kg2, mass of the moon = 7.36 × 1022 kg, mass of the earth = 6 × 1024 kg and the distance between the earth and the moon = 3.8 × 105 km.

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