Inertia

The diagrams below show the situations involving inertia.

Situation 1:

 

                                             Figure 1

When a driver inside a car applies brake suddenly (figure 1 a), the driver and passengers are move forwards. When the car accelerates (Figure 1 b), the driver and passengers will move backwards.

Situation 2:

 

                                                         Figure 2

 

Passengers in a bus will fall backwards when a bus starts suddenly from rest.

Situation 3:

                                                           Figure 3

Passengers in a moving bus fall forward when the bus stop suddenly.

Situation 4 :

 

                                         Figure 4

When the table cloth is suddenly pulled horizontally, the dishes on the table top still remain on the table.


Inertia

Inertia is the property of a body that tends to maintain its state of motion.

Newton's First Law (also known as Law of Inertia) explained by Sir Isaac Newton stated that

“Every object continues in its state of rest or uniform speed in a straight line unless acted upon by an external force”.

Relationship between Mass and Inertia

 

The adult who has more mass will show more reluctance to change her state of rest or motion. This property of the mass of a body which resists change from its state or motion is known as inertia.

The larger the mass, the larger the inertia.

Positive effect of inertia

The head of hammer can be tightened onto the wooden handle by applying a knock on the handle. The head of the hammer has a big mass and will remain in its state of motion, thus fitting it tighter on the handle.

In order to pour out the chili source, the bottle is moved down fast with the sudden stop. The sauce inside the bottle moves together  with the bottle. When the bottle stops suddenly, the sauces continue in its state of motion due the effects of its inertia.