Chapter 2, Problem 25A

A cat lies on the floor. Can you say that no force acts on the cat? Or is it correct to say that no net force acts on the cat? Explain.

To determine

Whether it is correct to say that no force acts on the car, and to say that no net force acts on the cat when it lies on the floor.

Answer to Problem 25A

When cat lies on the floor, then forces acts on it but net force on it is zero.

Explanation of Solution

Introduction:

Equilibrium is basically a state of no change in the state of the object. Thus, if the object is in equilibrium, then the net force on it is zero, that is,

  ${\displaystyle \sum F}=0$

When a cat lies on the floor, then it is in equilibrium. Hence, the net force on the cat is zero.

But it does not mean that no forces act on it. The weight of the cat always acts on it which is balanced by the support force on it by the floor, making the net force on it as zero.

Conclusion:

Hence, forces act on the cat even when it lies on the floor.