Why does a car apply a force to a wall?

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Discussion Overview

The discussion revolves around the physics of a car applying a force to a wall, particularly in the context of constant speed and friction. Participants explore the implications of forces during a potential collision and clarify concepts related to mass, acceleration, and friction.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant calculates net force using mass and acceleration but questions the validity of including friction as a separate mass.
  • Another participant asserts that friction is a force and does not have mass or acceleration, providing a definition of net force.
  • A participant highlights the need for clarity in the problem statement and asks about the specifics of the situation, such as whether the car collides with the wall.
  • There is a request for a diagram to aid in understanding the scenario better.
  • Participants express confusion over the initial post's assumptions and calculations, indicating a lack of clarity in the problem setup.

Areas of Agreement / Disagreement

Participants generally disagree on the interpretation of the problem and the role of friction, with some asserting that friction cannot be treated as a mass while others question the initial calculations and assumptions made.

Contextual Notes

Participants note that the original problem lacks a clear statement of the situation, which complicates the discussion. There are unresolved questions about the role of friction in collision scenarios and how to properly analyze the forces involved.

Who May Find This Useful

This discussion may be useful for individuals interested in understanding the dynamics of collisions, the role of forces in physics, and the conceptual challenges in applying Newton's laws to real-world scenarios.

Selfphysicslearner
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when we have 0 acceleration(constant speed) like a car traveling at a constant speed,
ƒnet=ma
ƒnet=(mobject+mfriction).(aobject+afriction)
let m object be 1500 kg.
m friction be 10 kg
a object be 0
a friction be 20m/s^2
so when we calculate fnet=-20*1600=-32 000 Newtons.
which means wall applies force towards car but the situation isn't like this.
questions:where did I make a mistake?
2-does friction have a mass or acceleration?
 
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Selfphysicslearner said:
when we have 0 acceleration(constant speed) like a car traveling at a constant speed,
ƒnet=ma
ƒnet=(mobject+mfriction).(aobject+afriction)
let m object be 1500 kg.
m friction be 10 kg
a object be 0
a friction be 20m/s^2
so when we calculate fnet=-20*1600=-32 000 Newtons.
which means wall applies force towards car but the situation isn't like this.
questions:where did I make a mistake?
2-does friction have a mass or acceleration?
This is not good. I guess from your name you are self-learning physics. There are some fundamental problems here. An object has only one mass. The idea of a friction mass is not valid. I can't imagine where you got that idea from.
 
Selfphysicslearner said:
friction have a mass or acceleration?
No. None of the two. Friction is a force.
Dimension mass times length divided by (time squared)
Units kgm/s2

So that is the mistake you make.

In your ##f_{\rm net} = m\, a##
##m## is the mass of the object​
##a## is the acceleration of the object​
##f_ {\rm net} ## is the net force on the object : the vector sum of one or more of the following:​
  • gravity
  • normal force
  • friction
  • external force(s)
 
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Selfphysicslearner said:
where did I make a mistake
There is problem in that you have not actually stated the situation / problem - except implied in the title.
It's sometimes very hard to get started with this sort of thing and you need to marshal your thoughts if you want to make progress with it.
Does the car hit the wall and come to a standstill?
Do you want to know the Force that acts on the car?
Where do you think friction comes into the collision calculations?
What do you know about collisions and the rules that we apply in calculations about collisions?
A diagram could help, perhaps - either draw one just for yourself or post it.
 
Selfphysicslearner said:
...but the situation isn't like this
What is the situation like then?
 
PeroK said:
I guess from your name you are self-learning physics.
Or learning self-physics.
 
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