Internal forces acting within a system of particles can alter

Options

A. The linear momentum as well as the kinetic energy of the system
B. The linear momentum of the system, but not the kinetic energy of the system
C. The kinetic energy of the system, but not the linear momentum of the system
D. Neither linear momentum nor kinetic energy of the system

Answer

To solve the question regarding the effects of internal forces acting within a system of particles, we will analyze the concepts of linear momentum and kinetic energy in relation to internal forces.

### Step-by-Step Solution:

1. **Understanding Internal Forces**:
- Internal forces are the forces that particles within a system exert on each other. For example, in a system of two particles, the force exerted by particle A on particle B is an internal force.

2. **Conservation of Linear Momentum**:
- According to the law of conservation of momentum, the total linear momentum of a closed system remains constant if no external forces are acting on it. Internal forces do not affect the total momentum of the system because they act in pairs (action-reaction pairs) and cancel each other out.

3. **Conservation of Kinetic Energy**:
- Kinetic energy can be altered by internal forces, especially in inelastic collisions where kinetic energy is transformed into other forms of energy (like heat or sound). However, in elastic collisions, kinetic energy is conserved.

4. **Evaluating the Options**:
- The question asks us to determine what internal forces can alter. Since internal forces do not affect the total linear momentum of the system, we can conclude that the linear momentum remains conserved.
- Regarding kinetic energy, it can be altered depending on the nature of the interactions (elastic vs inelastic).

5. **Conclusion**:
- Therefore, the correct statement is that internal forces acting within a system of particles can alter neither linear momentum nor kinetic energy of the system in the context of total system behavior. However, it's important to note that while momentum is conserved, kinetic energy can vary depending on the type of interactions.

### Final Answer:
The correct statement is: **Internal forces acting within a system of particles can alter neither linear momentum nor kinetic energy of the system.**