The quantity, when measured from different inertial reference frames, remains the same , among the following is

Options

A. Force
B. Velocity
C. Displacement
D. Kinetic energy

Answer

To solve the question, we need to identify which quantity remains the same when measured from different inertial reference frames. Let's analyze the options step by step.

### Step-by-Step Solution:

1. **Understanding Inertial Reference Frames**:
- Inertial reference frames are those that are either at rest or moving at a constant velocity. The laws of physics are the same in all inertial frames.

2. **Identifying the Quantities**:
- The question asks about quantities that remain the same across different inertial frames. Common quantities to consider include energy, momentum, force, and kinetic energy.

3. **Analyzing Kinetic Energy**:
- Kinetic energy (KE) is given by the formula:
\[ KE = \frac{1}{2} mv^2 \]
- Since kinetic energy depends on the velocity (v) of the object, which can change when viewed from different inertial frames, kinetic energy is not constant across different frames.

4. **Analyzing Total Energy**:
- Total energy includes both kinetic and potential energy. Since kinetic energy varies with velocity, total energy can also vary depending on the reference frame.

5. **Analyzing Force**:
- Force is defined as the rate of change of momentum. In an inertial frame, the laws of motion apply uniformly, and the force acting on an object remains the same regardless of the inertial frame from which it is observed. Thus, force can be considered constant across different inertial frames.

6. **Conclusion**:
- Among the options provided, the quantity that remains the same when measured from different inertial reference frames is **force**.

### Final Answer:
The quantity that remains the same when measured from different inertial reference frames is **force**.

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