what is inertia and why does it happen?
In: Physics
When it comes to movements, things typically want to keep doing what they’re doing. So a thing that’s not moving wants to stay not-moving, a thing that’s moving wants to continue moving, etc.
That’s inertia.
Let’s take the not-moving thing. Say it’s a block. Say it takes, oh, one Solarw0lf of energy to move this block from not-moving to moving. That’s more than it would take to keep the block moving (given friction, air resistance, etc, it could get a lot more complicated). But, generally, keeping the block moving would take significantly less than one Solarw0lf of energy because once the block is moving, it wants to stay moving.
Because that’s inertia.
Inertia is the idea that things will continue doing what they are already doing. This is typically applied to movement, as objects continue moving once pushed, unless pushed again, however the concept is applied to other things such as temperature. As of right now, scientists consider inertia (in the sense of movement) to be an intrinsic property of nature, however it is very possible that we will discover that inertia is caused by some other physical effect in the future.
Inertia is the resistance of a physical object to any change in how it’s moving. If the object is stationary, it doesn’t want to start moving. If the object is already moving, it doesn’t want to change how fast it’s moving or what direction it’s going. To get the object to start moving, or to change how it’s moving, we have to apply a force. The force we apply, and the resulting change in the way the object moves, can be used to define and measure the object’s “mass”, which is the amount of physical stuff in an object.
(The other way we define and measure an object’s mass is by the gravitational effect the object has on other objects. This connection between inertia and gravity seems weird and surprising, but it’s a really important feature of how the universe works.)
Edit: grammar/clarity.
Inertia is the ability of mass to resist a change in its velocity, it means that you have to push stuff in order to get it to move. If you’re in your car and brake suddenly and move forward into your seat belt, that’s inertia. your body is resisting the change in velocity that your car is experiencing. As for why … it’s a fundamental property of mass, it just is. It’s like asking why there’s light.
Inertia is the inherent property of mass that causes objects with mas resist changes to their velocities. It’s a fundamental property of the universe; it’s not “caused” by anything.
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