Can kinetic energy of a system be increased without applying any external force on the system?

If the kinetic energy of body increases then?

Can kinetic energy be negative? Why?

The potential energy of a system increase if work is done ……….

Kinetic energy can be negative.

Statement I: No external force acts on a system of two spheres which undergo a perfectly elastic head-on collision. The minimum kinetic energy of this system is zero if the net momentum of the system is zero. Statement II: If any two bodies undergo a perfectly elastic head-on collision, at the instant of maximum deformation. the complete kinetic energy of the system is converted to' deformation potential energy of the system.

State if each of the following statements is true or false. Give reasons for your answer. Total energy of a system is always conserved, no matter what internal and external forces on the body are present.

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

The internal energy of a system depend on what ?