The forces, which are considered for the analysis of an elementary profile of a gravity dam under empty reservoir condition, are i) Water pressure ii) Self weight iii) Uplift iv) Pressure due to earthquake The correct answer is A. Only (ii) B. (i), (ii) and (iii) C. (i), (ii) and (iv) D. (i), (ii), (iii) and (iv)

The correct answer is B. (i), (ii) and (iii).

Water pressure is the force exerted by water on the dam. It is a hydrostatic force, which means that it acts in all directions and is proportional to the depth of the water. Self weight is the weight of the dam itself. It is a gravitational force that acts vertically downwards. Uplift is the force exerted by the water on the underside of the dam. It is a hydrostatic force that acts in the upward direction. Pressure due to earthquake is not considered for the analysis of an elementary profile of a gravity dam under empty reservoir condition.

The following is a brief explanation of each option:

• Option (i): Water pressure is the force exerted by water on the dam. It is a hydrostatic force, which means that it acts in all directions and is proportional to the depth of the water. Water pressure is the most important force to consider in the analysis of a gravity dam.
• Option (ii): Self weight is the weight of the dam itself. It is a gravitational force that acts vertically downwards. Self weight is a secondary force to consider in the analysis of a gravity dam.
• Option (iii): Uplift is the force exerted by the water on the underside of the dam. It is a hydrostatic force that acts in the upward direction. Uplift is a secondary force to consider in the analysis of a gravity dam.
• Option (iv): Pressure due to earthquake is not considered for the analysis of an elementary profile of a gravity dam under empty reservoir condition. Earthquakes are a dynamic load, which means that they act in a non-uniform manner. The analysis of a gravity dam under earthquake loading is a complex problem that requires specialized knowledge.