Chapter 4, The Forces, focuses on the forces between different bodies. A force is simply defined as the push or pull effect on an object. This occurs when two bodies interact with one another. Thus, force tends to change its velocity.
Force has both magnitude and direction, which implies that it is a vector quantity. The direction of force is easy to find out and is usually the direction in which force is applied/acting. Mother nature is home to numerous attractive forces. Some examples include the forces of gravity, magnetic, electrostatic & electric fields.
Force can be mathematically explained by the formula:
Fg= Gm1m2/ d2
Here, F denotes the force of attraction, G is the gravitational constant with a value of
6.67 × 10-11 Nm2/kg2, d indicates distance and m1, m2 are the masses of objects 1 & 2.
Both gravitational and electric forces act along a line drawn between the objects. They also tend to decrease with the square of the distance between them. This is a common law that exists. According to Coulomb's law, the magnitude and sign of the electric force between the objects are determined by the electric charges rather than the mass of an object.
If the product of charges of objects 1 & 2 is positive, the force between them is repulsive. On the other hand, if the product of charges is negative, the force between them is attractive. This chapter also focuses on the geostationary orbit of the Earth along with the formula to compute the gravitational force at a particular height.