If a car moves consistently at 80 kmh and it weighs at 600kg, is it not generating any force? since you know, a=0, am I stupid or is Newton ?
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The only correct answers in this thread are the ones that mention that *sum of forces* = m*a. A car moving at a constant speed has a net 0 sum of forces. Just like a person standing still on earth. However for the person, gravity is still pulling them towards the center of the earth, just like the surface of the earth is resisting you getting pulled through it (which are equal and opposite, thus 0 net force). The only time the net force will be greater than zero is if your speed (really velocity, which is the same but with a direction) is changing, and changing velocity over time is the definition of acceleration.
Your car’s engine is very definitely “generating” a force, but if you aren’t accelerating then its because that force is being countered by friction on the road and air resistance adding up to be equal and opposite to that provided by the car.
I think you are confusing force with momentum. If the car hit a wall there would be an impact force due to the momentum.
Force describes an interaction between two or more objects. Any type of collision will involve one of the bodies either speeding up or slowing down.
You might be thinking of kinetic energy which can be described using mass and velocity.A moving car has kinetic energy.
When it hits something it applies force and experiences force in return. But the amount of force is dependent on how fast the kinetic energy is transferred. So if a car hits a brick wall the deceleration is very quick and there is a lot of force, destroying the car. But if the car hits a comically giant cushion the deceleration happens slowly and the force and therefore damage is less, even if the kinetic energy was the same. (This is why cars have airbags and crumple zones-they essentially act as cushions to slow the deceleration of the passengers).
Force is a change. If you are sitting on the hood of the car going 80 kmh you won’t feel anything.
If you are at rest and it hits you, your speed changes quickly and that’s where the force comes from
The engine is generating force to keep the car moving at a constant speed against air resistance, but the overall speed of the car is not creating any force.
In other words, the force the car is generating is determined by the mass and acceleration of the engine components, not the overall speed of the car.
You have to generate force to keep a car moving at constant speed on Earth because of air resistance. Air resistance creates a force on the car so you must therefore apply a force to cancel it out.
If you were in space, then a car (or any object) moving at constant velocity wouldn’t be generating any force.
‘It’s”, not generating force. Force is being applied to over come the inertia and resistance, in order that it moves. Whilst moving it has momentum.
…if it crashes into a wall, a portion of that amassed energy will become force, sound, heat, light in order to overcome the mass of the wall, it’s inertia, resistance.
…it’s all about the state of the energy at anyone point in time.
You are sitting in the car at constant speed and you wont feel the force of the car against you either. The force you would feel at a crash is actually the deceleration (negative acceleration)
It depends on the rules of your scenario (simplifying assumptions)…in the real world cars experience deceleration forces due to dragg and air resistance etc. For a car to move at a consistent velocity of 80 kph, then it must also have some small acceleration which cancels out with the negative forces.
The concept of energy and the one of impulse have an intertwined history. At some point physicists debated this same question. Dead Force and Living Force were terms used to describe them. Newton and Descartes/Leibnitz where in one of those two “camps”.
This is a **great** video with historical explanation of those two terms, and their relation with the First Law of Thermodynamics:
[https://youtu.be/a9c7u-FM-Wc](https://youtu.be/a9c7u-FM-Wc)
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