how is newton's 1st law of motion contained in 2nd law??

Answer 1

The First Law is just a special case of the Second Law for which the net external force is zero.

Answer 2

Newton's Second Law of Motion implies that unless & until an external force acts on a body, the body does not change its state of motion (since F=ma, & a=0 for bodies in rest as well as in uniform linear motion). And, if you carefully observe, this is what Newtons First Law of Motion states, that a body at rest always wants to be at rest & a body in motion always wants to continue its motion in a straight line at constant speed, unless an external force acts on a body. That's why the 1st law is said to be contained in the 2nd law. Hope your doubt is cleared now, Virat. But don't ask me to prove it now, because it is a fact, a very interesting one indeed, that NONE of the laws that Newton had founded can be theoretically proved, be it the Law of Gravitation, be it the Laws of Motion, or any other law proposed by Newton in Physics.

Answer 3

in the 1st law, it only states that objects tend to stay at rest or in motion unless acted upon net external force, in the 2nd law, it states that acceleration is directly proportional to the net external force