Q1: C_d is always __________ C_c.

ANS:A - greater than

In fluid dynamics, CdC_dCd​ (drag coefficient) and CcC_cCc​ (lift coefficient) are dimensionless quantities used to describe the forces acting on an object in a fluid flow. The relationship between CdC_dCd​ and CcC_cCc​ can vary depending on the specific context and the geometry of the object:

1. Drag Coefficient (CdC_dCd​):
   • Drag coefficient represents the ratio of the drag force experienced by an object to the dynamic pressure of the fluid flow.
   • It is influenced by factors such as the shape, size, and surface roughness of the object.
2. Lift Coefficient (CcC_cCc​):
   • Lift coefficient represents the ratio of the lift force (perpendicular to the flow direction) experienced by an object to the dynamic pressure of the fluid flow.
   • It is significant in the context of aerodynamics, where it determines the effectiveness of generating lift.

Relationship Between CdC_dCd​ and CcC_cCc​:

• Context-Dependent: The relationship between CdC_dCd​ and CcC_cCc​ depends on the specific characteristics of the flow and the object:
  • For some shapes and conditions, CdC_dCd​ can be greater than CcC_cCc​.
  • For other shapes and conditions, CdC_dCd​ can be less than CcC_cCc​.
  • In certain idealized cases (such as for a sphere in a certain range of Reynolds numbers), CdC_dCd​ can be approximately equal to CcC_cCc​.

Conclusion:

Therefore, CdC_dCd​ (drag coefficient) can be either more or less than CcC_cCc​ (lift coefficient), depending on the shape and conditions of the object in the fluid flow. The relationship between CdC_dCd​ and CcC_cCc​ is not fixed and can vary based on the specific aerodynamic or hydrodynamic characteristics of the flow and the object.