Laws of Motion - SS1 Physics Past Questions and Answers - page 1

Newton's first law of motion, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will continue to move at a constant velocity in a straight line unless acted upon by an external force. This law essentially describes the concept of inertia, which is the tendency of an object to resist changes in its state of motion.

For example, if a book is placed on a table, it remains at rest until an external force, such as a person pushing it, is applied. Similarly, if a ball is rolling on a smooth surface, it will continue to roll with a constant velocity unless acted upon by a force, such as friction or an applied force.

Newton's second law of motion states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. Mathematically, it can be expressed as F = ma, where F represents the net force, m represents the mass of the object, and a represents the acceleration produced.

For example, consider a car being pushed with a certain force. According to Newton's second law, if the same force is applied to a smaller car with less mass, it will result in greater acceleration compared to a larger car with more mass. This law helps us understand the relationship between force, mass, and acceleration in various physical scenarios.

Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that whenever an object exerts a force on another object, the second object exerts a force of equal magnitude but in the opposite direction on the first object.

For example, when you walk, your foot exerts a force backwards on the ground. As a result, according to Newton's third law, the ground exerts an equal and opposite force forward on your foot, propelling you forward. Similarly, when you swim, your arms push the water backward, and in response, the water exerts a force on your arms, propelling you forward.