16.3.2. Drag Force and Power Computation

Try these first

1. 1.

   What is drag force?

   Hint

   Consider what happens as an object moves in water or air.

2. 2.

   How do you compute shear stress?

   Hint

   Remember the relationship between force and area in a fluid.

3. 3.

   What does the Reynolds number indicate?

   • A measure of pressure
   • A ratio of inertial to viscous forces
   • A method of calculating drag

   Hint

   Think about its role in fluid dynamics.

4. 4.

   True or False: Drag force is only affected by viscosity.

   • True
   • False

   Hint

   Consider other factors involved.

5. 5.

   An automobile prototype has a drag coefficient of 0.35, a frontal area of 2.5 m², and tests show a velocity of 80 km/h in a wind tunnel. Calculate the drag force for the prototype in N.

   Hint

   Remember to convert velocity properly before plugging values into the drag force formula.

6. 6.

   For dynamic similarity, a model scale is 1:10 with a velocity of 5 m/s. If you need to find the velocity of the full-scale object, what is it?

   Hint

   Think about how scaling affects velocity and ratio calculations.