Chapter 3, Problem 70A

To determine

The examples of falling objects for which air resistance can and cannot be ignored.

Explanation of Solution

Introduction:

If the falling objects have smaller surface area compared to its volume then for this air resistance can be ignored while if the falling object have larger surface area compared to its volume then for this air friction cannot be ignored.

Consider a cricket ball falling from sky. Its surface area is very small as compare to its volume then for this, we can ignore the air resistance.

Consider another example of a man with parachute falling down from the sky. The surface area of parachute is very large then in this case air resistancecannot be ignored. Due to the presence of air resistance, the man falls down slowly.

Conclusion:

The effect of air resistance is directly propositional to the surface area of the falling object.