There are three Newton's laws of motion namely first second and third laws we can derive
Answers
There are three Newton's laws of motion namely first,second and third laws.We can derive
medium
MEDIUM
Share
Save
ANSWER
Newton's second law of motion is F=ma
That is we have:-
F=m(v−
t
u
) thus, Ft=mv−mu.
Now,When F=0, then v=u. That is the absence of force,The object continue to move with same velocity
throughout.
Now,when F=0 and u=0, then v=0. That is , an object at rest if no force is acting on it.
Thus,
Newton's first law is derived from the second law.
Now let us consider a system of 2 bodies 1&2 and considers that there is no external force acting.
Now let F
12
be the force acting on 2 by 1 and F
21
be the force acting on 1 by 2.
The rate of change of momentum of 1=
dt
dp
1
and rate of change of momentum of 2=
dt
dp
2
Thus, according to Newton second law of motion F
12
=
dt
dp
2
and F
21
=
dt
dp
1
Adding both the above equation, we get:-
F
12
+F
21
=
dt
dp
2
+
dt
dp
1
=d(p
2
+p
1
)/dt
We know that, no force is applied.
Thus momentum change will also be 0 change in velocity occurs.
Thus
dt
d(p
1
+p
2
)
=0
Therefore, F
12
+F
21
=0
That is F
12
=−F
21
Thus, Newton's third law is proved with Newton's second law.
Hence,