What is the acceleration of a car at constant speed?

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Discussion Overview

The discussion centers around the concept of acceleration in the context of a car traveling at a constant speed, specifically addressing whether the acceleration is zero or if it relates to opposing forces such as drag and rolling resistance. The scope includes conceptual clarification and technical explanation of acceleration and its definitions.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that if a car is traveling at a constant speed, the acceleration is zero, provided resistive forces are not considered.
  • Others argue that to maintain constant velocity against resistive forces, the engine must exert a force, suggesting a nuanced view of acceleration in relation to these forces.
  • A later reply questions the framing of acceleration as being equal to forces like drag and rolling resistance, emphasizing that acceleration is a measure of the rate of change of velocity, not a force itself.
  • Another participant highlights the distinction between speed and velocity, indicating that this distinction is important for a thorough understanding of acceleration.
  • Some participants clarify that constant speed does not imply zero acceleration, as an object can have acceleration while maintaining constant speed if it is moving along a curved path.
  • It is noted that the definition of acceleration does not depend on the forces acting on an object, reinforcing that if velocity is constant, acceleration is zero regardless of external forces.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between constant speed and acceleration, with no consensus reached on whether acceleration can be considered zero in the presence of resistive forces.

Contextual Notes

The discussion reflects varying interpretations of key definitions, such as acceleration and the distinction between speed and velocity, which may lead to confusion in the context of forces acting on a moving car.

BoredButCurious
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If a car is traveling at a constant speed of say, 60MPH, is the acceleration of the car 0, or is it equal to the drag and rolling resistance it's facing?
 
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BoredButCurious said:
If a car is traveling at a constant speed of say, 60MPH, is the acceleration of the car 0, or is it equal to the drag and rolling resistance it's facing?
What do you think and why? What is the definition of acceleration?
 
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If not considering resistive forces, the acceleration is zero.
But if we do consider them, then they are always opposing the motion of the car. To keep the velocity of the car constant, the engine has to be kept running, else resistive forces slow u down to rest.
So, a force is applied by the engine just to overcome the resistive forces to keep the car moving with constant velocity.
I hope you understood :-)
 
BoredButCurious said:
If a car is traveling at a constant speed of say, 60MPH, is the acceleration of the car 0, or is it equal to the drag and rolling resistance it's facing?

Read your question again. The last part asks if an acceleration (the acceleration of the car) is equal to a force (drag/rolling resistances are forces). That cannot be correct.
 
You should also distinguish between speed and velocity is you are dealing with Acceleration in a thorough way.
 
[USER=569844]@navin[/USER] said:
If not considering resistive forces, the acceleration is zero.
But if we do consider them, then they are always opposing the motion of the car. To keep the velocity of the car constant, the engine has to be kept running, else resistive forces slow u down to rest.
So, a force is applied by the engine just to overcome the resistive forces to keep the car moving with constant velocity.
I hope you understood :-)

I'm sorry but your explanation is overly complicated and confusing and has little to do with the OP's question.

BoredButCurious said:
If a car is traveling at a constant speed of say, 60MPH, is the acceleration of the car 0, or is it equal to the drag and rolling resistance it's facing?

As Phinds said, look at the definition of acceleration: the rate of change of velocity.
 
As pointed out already, all such confusion arises because of not completely understanding a definition. First, constant speed does not mean zero acceleration. An object could be going on a curved path at constant speed. The object has an acceleration. Zero acceleration means constant velocity. Also to be noticed is that the definition of acceleration does not involve any information about forces. Acceleration is a kinematic quantity. Irrespective of what forces are acting, if the velocity is constant, the acceleration is zero.
 

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