What Is The Acceleration Of A Car At Constant Speed? - Physics Forums

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What is the acceleration of a car at constant speed?
  • Context: High School
  • Thread starter Thread starter BoredButCurious
  • Start date Start date Oct 2, 2015
  • Tags Tags Acceleration Car Constant Constant speed Force Speed
Click For Summary SUMMARY

The acceleration of a car traveling at a constant speed, such as 60 MPH, is zero when considering only the definition of acceleration as the rate of change of velocity. While resistive forces like drag and rolling resistance act against the car's motion, they do not contribute to acceleration; instead, they require the engine to exert a force to maintain constant velocity. Therefore, the car's acceleration remains zero as long as its speed does not change, regardless of the forces acting on it.

PREREQUISITES
  • Understanding of basic physics concepts, particularly kinematics.
  • Familiarity with the definitions of speed, velocity, and acceleration.
  • Knowledge of forces, including drag and rolling resistance.
  • Ability to distinguish between constant speed and constant velocity.
NEXT STEPS
  • Study the principles of kinematics in physics, focusing on acceleration and velocity.
  • Explore the effects of drag and rolling resistance on vehicle dynamics.
  • Learn about Newton's laws of motion and their application in real-world scenarios.
  • Investigate the differences between speed and velocity in various contexts.
USEFUL FOR

This discussion is beneficial for physics students, automotive engineers, and anyone interested in understanding the dynamics of motion and the forces acting on vehicles.

BoredButCurious Messages 1 Reaction score 0 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? Physics news on Phys.org
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phinds Science Advisor Insights Author Gold Member Dearly Missed Messages 19,378 Reaction score 15,614
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? @navin Messages 5 Reaction score 1 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 :-) CWatters Science Advisor Homework Helper Gold Member Messages 10,546 Reaction score 2,324
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. sophiecentaur Science Advisor Homework Helper Messages 30,331 Reaction score 7,451 You should also distinguish between speed and velocity is you are dealing with Acceleration in a thorough way. Drakkith Mentor Messages 23,198 Reaction score 7,679
[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. Chandra Prayaga Science Advisor Messages 652 Reaction score 150 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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