In Newtonian mechanics which parameter apply external force ?

The scientist who said that "an object in motion will remain in same motion as long as no external force is applied" is

Which type of forces are responsible in explosion of chemical bomb internal or external forces?

Assertion : A body can be at rest even when it is under the action of may number of external forces Reason : Because vector sum of the all external forces is zero .

Total energy of a system is always conserved , no matter what internal and external forces on the body are present .

Newton's.. . law of motion shows the relation between external force acting on the object and change in its momentum.

The rate of change of total momentum of a many -particle system is proportional to the external force/sum of the internal forces on the system .

Is it possible to double the length of a metallic wire by applying force over it ?

What is the area under the graph of F to x ? (F = external force , x = change of spring length )