21. The Earth is acted upon by gravitation of Sun, even though it does not fall into the Sun. Why?

According to Newton’s first law of motion, an object in motion tries to move in straight-line at a constant speed unless external pressure is not applied. When the Earth comes close to the Sun that has a large gravitational force, the path of the Earth is altered due to the unbalanced force of gravity on it. The Sun exerts an attractive force on the Earth, accelerating the Earth directly towards the Sun. It moves toward the Sun as described by Newton’s second law. To avoid falling into the Sun, the Earth also counteracts the force that is pulling it towards the Sun. Thus, a force, which tends to make a body move in a curved path, is called a centripetal force is applied by the Earth. Therefore, we can say that the gravitational force is responsible for providing the necessary centripetal force which allows the Earth to move around the Sun in a defined orbit. Gravitational attraction of the Sun deflects the Earth from a straight path.