Understanding Inertia


Have you ever stood in a bus which starts suddenly from rest? You are likely to fall backwards. If the moving bus stops suddenly, you are likely to fall forward. 


Have you noticed that a bigger vehicle (Truck) is more difficult to stop than a light vehicle (Motorcycle)?

What Causes This to Happen?


When the bus moves suddenly from rest, our feet are carried forward but the inertia of our body tends to keep us at rest. This causes our body to fall backwards. When the bus stops suddenly, our feet are brought to rest, but the inertia of our body tends to continue its forward motion. This causes our body to fall forward.

The two situations above show that our body has an inbuilt resistance to any change in its state of rest or motion. This reluctance is called inertia.

“The inertia of an object is the tendency of the object to remain at rest or, if moving, to continue its uniform motion in a straight line.”

The concept of inertia was explained by Sir Isaac Newton in the first law of motion.


It is to be put in mind that inertia is dependent upon the mass of the object. The larger the mass, the larger its inertia. Hence, we can see that its harder to push a heavy box than to push a lighter box.


Many phenomena in our daily lives involve inertia. We make use of the positive effects of inertia to solve some of our daily problems. On the other hand, there are many negative effects of inertia that can endanger our lives and wee need to find ways to reduce them.

Examples are: It’s more effective to fit the head of a hammer (with a higher mass) tightly onto the wooden handle by hitting the bottom of the handle against a hard surface. The head which has a larger mass remain in its state of motion and thus presses itself more tightly around the handle.

Inertia also can be observed in ice skaters where inertia enables ice skaters to keep gliding over the surface of ice at an almost constant speed in a straight line effortlessly.

Ways to reduce inertia in vehicle:

1. Seat belts help to tighten the passenger during collision. This is to prevent the passenger from being thrown forward due to inertia.

2. Air bag is fitted inside the steering wheel. It provides a cushion to prevent the driver from hitting the steering wheel.


Anonymous said...


MUGISHA Joel said...

I like the text, we can appreciate what physics can explain to us in our daily life.

Anonymous said...

thank you for the information...i prefer reading it from the internet than the textbook...HUHUHU...:P!

Anonymous said...

thank you for the information..it helped me..i prefer reading from the internet than from the text book.:P

Anonymous said...

Wonderful examples of how inertia is evident in every day life.Thank you

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