Question

class 9th NCERT Book science ch 9th force and low and motion notes​

Answer 1

Required Answer:

☑Introduction to Force

☑A force is an effort that changes the state of an object at rest or at motion. It can change an object’s direction and velocity. Force can also change the shape of an object.

☑Balanced and Unbalanced Forces

☑When balanced forces are applied to an object, there will be no net effective force acting on the object. Balanced forces do not cause a change in motion.

☑Unbalanced forces acting on an object change its speed and/or direction of motion. It moves in the direction of the force with the highest magnitude.

☑First Law of Motion

☑A body continues to be in the state of rest or uniform motion in a straight line unless acted upon by an external unbalanced force. The First Law is also called the Law of Inertia.

☑Second Law of Motion

☑The rate of change of momentum of an object is directly proportional to the applied unbalanced force in the direction of the force.

☑Third Law of Motion

☑Newton’s 3rd law states that every action has an equal and opposite reaction. Action and reaction forces are equal, opposite and acting on different bodies.