Question 1

How Can Newton's First Law of Motion Be Obtained from the Second Law of Motion?

Accepted Answer

When net force is zero and when moving with constant speed. Newton's first law of motion states that a body at rest will remain at rest unless an outside force acts on it, and a body in motion at a constant velocity will remain in motion in a straight line unless acted upon by an outside force.  If a body experiences an acceleration ( or deceleration) or a change in direction of motion, it must have an outside force acting on it. Outside forces are sometimes called net forces or unbalanced forces. The second law of motion states that if an unbalanced force acts on a body, that body will experience acceleration (or deceleration), that is, a change of speed.  So,  Outside forces are sometimes called net forces. If net force acting on a moving body is zero, the body will be at a constant velocity. Thus Newton's first law of motion can be obtained from the second law of motion.

Question 2

How Does the First Law of Motion Lie in the Second Law of Motion?

Accepted Answer

Newton's first law of motion states that a body will stay at rest or continue its path with constant velocity unless an external force acts upon it. Newton's second law of motion states that the net force that acts upon a body is equal to the mass of the body multiplied by the acceleration due to the net force. In other words, Fnet=ma. Now, one can argue that Newton's second law of motion leads to the first law. Consider this: since Fnet=ma, with zero net force (no external forces), 0=ma. Now, m is some finite positive value. In other words, this means that a=0. By definition, then, there is constant velocity (possibly constant zero velocity). Thus, it seems that Newton's second law of motion leads to the first law.

Question 3

What Are the Two Factors that Affect Newton's Second Law?

Accepted Answer

The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object.