Non-Existent Force: What Does it Mean & Why?

[Robokapp]

I don't know if this was already adressed, but I saw in my book the term of Non-existent force and until today I didn't get what it is referring to...why it's non-existent.

Assuming you're in a car with linear motion, constant velocity...zero acceleration. You hit your break as hard as you can. You will be pushed forward and collide with the steering weel.

Question: Where do you get the force that leads to you moving in report to the steering weel if you were at equilibrium with the rest of the car and the brake affects the car, not you?

The 5-step process and Newton's 3 laws make no mention of this. The more I'm trying to apply them the more i feel like an idiot.

Any help? Some info...whatever?

 

[Fermat]

Centrifugal force is a called both a ficticious force and a non-existant force.
When traveling in a circle, there is a centriptal force on your body directed towards the centre of rotation. Centripetal force is an actual, real force.

Centrifugal force is suppposed to be numerically equal to centripetal force but acting in the exact opposite direction, radially outwards. Not so. There is no force pusing you out, that is an inertial effect!

Centrifugal force is still used though, in astrophysics or something like that - it makes it easier to visualise things perhaps - I'm not sure exactly.

When traveling in a circle, your body will naturally want to travel in a straight line. If a centripetal force pushed you radially inwards, then the inertia of your body, which will make it want to travel in a straight line, will "push" outwards. That is the inertial effect. The inertia of your body trying to resist an accelerating force.

When the car crashes, you are not pushed forwards, rather it is the car that is being pushed backwards. The inertia of your body wants it to continue in a straight line - forwards - and so "pushes" against the car steering wheel as it very quickly slows down (decelerates).

 

[sir-pinski]

The term "non-existent force" refers to a force that is not actually present or acting on an object. In the scenario described, the force that causes you to move forward and collide with the steering wheel is not a physical force, but rather the result of the car's deceleration. This is known as an inertial force, which is not a true force but rather a consequence of an object's motion or change in motion. In this case, the force that causes you to move forward is not actually acting on you, but rather the result of the car's brakes slowing down the car's motion.

This concept can be confusing because we often think of forces as tangible and directly acting on objects. However, in physics, forces are defined as an interaction between two objects that causes a change in motion. In this scenario, the force of the car's brakes acting on the car is what causes the car to slow down, but it is the car's inertia and your own inertia that causes you to move forward.

As for Newton's laws, the first law states that an object at rest will remain at rest unless acted upon by a net force, while an object in motion will remain in motion with constant velocity unless acted upon by a net force. In this scenario, the car and you were both at rest (equilibrium) before the brakes were applied. When the brakes are applied, the car experiences a net force in the opposite direction of its motion, causing it to slow down. However, you were already in motion with the car, so your inertia causes you to continue moving forward until you are stopped by the steering wheel.

It's important to remember that forces are always acting on objects, but it's the net force that determines the object's motion. In this case, the net force acting on the car is the force of the brakes, while the inertial force acting on you is the result of the car's deceleration. I hope this helps clarify the concept of non-existent force and its role in this scenario. Keep practicing and applying Newton's laws, and don't feel like an idiot - physics can be tricky but with practice, it will become easier to understand.