Two identical trains `A` and `B` move with equal speeds on parallel tracks along the equator. A moves from east to west and `B` moves from west to east. Which train will exert greater force on the track?

Options

A. `A`
B. `B`
C. they will exert equal force
D. the mass and the speed of each train must be known to reach a conclusion.

Answer

To determine which train, A or B, exerts a greater force on the track, we need to consider the effects of the Earth's rotation and the relative motion of the trains.

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- Train A is moving from east to west.
- Train B is moving from west to east.
- Both trains are moving at equal speeds and are identical.

2. **Earth's Rotation**:
- The Earth rotates from west to east. This means that at the equator, objects are moving eastward due to this rotation.

3. **Relative Velocity**:
- For Train A (moving east to west), its velocity relative to the ground is its speed minus the rotational speed of the Earth.
- For Train B (moving west to east), its velocity relative to the ground is its speed plus the rotational speed of the Earth.

4. **Net Force Calculation**:
- The force exerted by each train on the track is influenced by the net effect of their velocities.
- The effective force on the track can be considered as the weight of the train plus the additional force due to the relative motion with respect to the Earth's rotation.

5. **Comparing Forces**:
- Train A, moving against the Earth's rotation, has a lower effective speed relative to the ground.
- Train B, moving with the Earth's rotation, has a higher effective speed relative to the ground.
- Therefore, Train B will exert a greater force on the track due to its increased effective speed.

6. **Conclusion**:
- Train B, which moves from west to east, exerts a greater force on the track compared to Train A.

### Final Answer:
Train B will exert greater force on the track.