what is inertia and it's law
Answers
Inertia is the characteristic that objects have of continuing to move at the same speed and in the same direction (or of continuing not to move) unless and until a force operates on them to change speed and/or direction. So if an object starts or stops moving or changes speed and/or direction, you can know a force has acted.
If you can measure that change in motion, you have the acceleration. And if you multiply the acceleration by the mass, you have the force.
All this comes from the confidence of knowing that inertia means that without any force, the object would have continued unchanged.
Inertia is useful in other ways too. You know that when you swing a hammer at a nail, the force (and consequent movement) applied to the hammerhead means it will continue swinging until the head of the mail stops it…and in doing so the hammerhead will have overcome the inertia of the nail (and the much larger friction) to drive it into the material.
And it is inertia (rotational inertia) which means that your car doesn’t stop when the power stroke is over in the engine. The power stroke rotates the crankshaft, and inertia keeps it rotating until the next power stroke. The flywheel is specifically designed to maximize this inertia and smooth the motion.
The entire universe exists in the form it does because of the inertia following the big bang. The unimaginable explosion that was the big bang is what started the universe expanding. But since that first nanosecond, and for the next 14 million years, inertia has kept that going, and the Earth moving around the sun, and spinning and…
Inertia literally means no energy. And that is why I’ll be relaxing at the end of a busy day watching TV.