Question

Newton gave the law of gravitation. It is also called universal law of gravitation because it is applicable to all the bodies having mass. According to this law, any two bodies of masses m₁ and m₂ separated by a distance r attract each other with a force F = . Here, G is a constant whose value is an absolute constant. The value of G does not depend upon masses of two bodies, distance between the bodies, nature of bodies. That is why G is called Universal gravitational constant. As the value of G is extremely small, therefore, gravitational force between any two ordinary objects will be really week. However, the gravitational force becomes appreciable when even when one of the objects has a larger mass. Weight of a body is the force with which the body is attracted towards the centre of the earth. It is given by W= mg, where g is acceleration due to gravity. At the centre of earth g = 0. As we move above or below the surface of earth, value of g goes on decreasing. (i) Acceleration of free fall is called acceleration due to gravity (g) whose value is (a) 9.8 m/s² (b) 19.6 m/s² (c) 0.98 m/s² (d) 98 m/s² (ii) If earth is taken as a sphere of mass M and radius R, value of acceleration due to gravity (g) on the surface of earth is given by (a) G = gM / R² (b) g = GM / R² (c) g = GM /R³ (d) g = G /MR² (iii) At the centre of earth, value of g is (a) 9.8 m/s² (b) zero (c) -9.8 m/s² (d) 4.9 m/s² (iv) A body of given mass weighs (a) Maximum at the centre of the earth (b) More at a height above the surface of earth (c) More at a depth below the surface of earth (d) Maximum at the surface of earth. (v) A body weighs 40 kg on the surface of earth. At the centre of the earth, its mass and weight respectively are (a) 40 kg, 40 kg (b) 40 kg, zero (c) zero, zero (d) zero, 40 kg ​

Answer 1

Answer:

Sir Isaac Newton’s inspiration for the Law of Universal Gravitation was from the dropping of an apple from a tree.

Newton’s insight on the inverse-square property of gravitational force was from intuition about the motion of the earth and the moon.

The mathematical formula for gravitational force is

F

=

G

Mm

r

2

where

G

is the gravitational constant.

Key Terms

induction: Use inductive reasoning to generalize and interpret results from applying Newton’s Law of Gravitation.

inverse: Opposite in effect or nature or order.