Question

A change in kinetic energy can be brought in a system by:

• A. Only external forces
• B. Only internal forces
• C. Only conservative forces
• D. External forces, Internal forces and Conservative forces
  

Answer 1

Answer: (D)

External forces, Internal forces and Conservative forces

Both external and internal forces can change the kinetic energy of the system, hence it can be external as well internal forces that can change kinetic energy.

Similarly kinetic energy can also change due to conservative forces as gravitational forces when ball thrown from a height gains kinetic energy as it descends.