17.5.1. Definition of Friction and Pressure Drag

Try these first

1. 1.

   Define friction drag.

   Hint

   Think about what happens at the surface of an object moving through water.

2. 2.

   What is the drag coefficient?

   Hint

   Consider the factors that affect how drag is calculated.

3. 3.

   What causes friction drag?

   • Shape of the object
   • Viscosity of the fluid
   • Speed of the fluid

   Hint

   Consider what happens at the surface level.

4. 4.

   True or False: Pressure drag only occurs in turbulent flow.

   • True
   • False

   Hint

   Think about the scenarios in which pressure drag can be observed.

5. 5.

   A car with a frontal area of 2.4 m² and a drag coefficient of 0.32 moves at 30 m/s. Calculate the drag force it experiences in the air where the density is 1.225 kg/m³.

   Hint

   Ensure you substitute all values correctly in the drag force equation.

6. 6.

   A swimmer with a body area of 0.7 m² experiences a drag force of 5 N while moving at 1.5 m/s in water with a density of 998 kg/m³. Find the swimmer's drag coefficient.

   Hint

   Use the provided values to calculate the drag coefficient.