Weight vs Normal Reaction
Weight:
- Weight is the force exerted by gravity on an object due to its mass.
- It is always directed towards the center of the Earth.
- Weight is a vector quantity, meaning it has both magnitude and direction.
- The weight of an object can vary depending on the strength of the gravitational field it is in.
Normal Reaction:
- Normal reaction is the force exerted by a surface on an object in contact with it.
- It acts perpendicular to the surface and prevents objects from passing through each other.
- Normal reaction is a contact force and only exists when there is contact between two objects.
- It is always equal in magnitude and opposite in direction to the force exerted by the object on the surface (Newton's third law of motion).

Difference between Weight and Normal Reaction:
1. Direction: Weight always acts vertically downward towards the center of the Earth, while normal reaction acts perpendicular to the surface of contact.
2. Causes: Weight is caused by gravity, while normal reaction is caused by contact between two surfaces.
3. Magnitude: Weight depends on the mass of the object and the strength of the gravitational field, while normal reaction is equal in magnitude to the force exerted by the object on the surface.
4. Independence: Weight is independent of the contact between two objects, while normal reaction only exists when there is contact.
5. Effect on Motion: Weight can cause objects to accelerate towards the Earth, while normal reaction can balance the weight and prevent objects from sinking into surfaces.
In conclusion, weight and normal reaction are two different forces that play a crucial role in understanding the interactions between objects in contact with each other and with the Earth's gravitational field.