Does Constant Engine Power Guarantee Constant Acceleration?

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Homework Help Overview

The discussion revolves around the relationship between constant engine power and acceleration in vehicles, specifically questioning whether constant power guarantees constant acceleration. Participants explore the implications of power, forces acting against acceleration, and the nuances of real-world scenarios versus theoretical assumptions.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the implications of constant power on acceleration, questioning whether acceleration can remain constant given the presence of opposing forces such as wind resistance and friction. There is also a consideration of the difference between theoretical scenarios and practical applications, such as the performance of a car versus a rocket in space.

Discussion Status

The discussion is active, with participants raising questions about the assumptions underlying the original statement. Some have provided insights into additional forces that affect acceleration, while others are exploring the implications of these forces on the relationship between power and acceleration. There is no explicit consensus yet, as participants continue to analyze the problem from different angles.

Contextual Notes

Participants note that the problem may not account for real-world factors such as friction and air resistance, which complicate the relationship between power and acceleration. There is also a distinction made between theoretical models and practical scenarios, particularly in the context of different types of vehicles.

jim_ringo
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Homework Statement


a cars engine produces constant power therefore the cars speed will increase at a constant acceleration.

is this true or false


Homework Equations


Power=w/t
work=fd
so P=mad/t




The Attempt at a Solution



so if p is constant it appears a must be constant. Therefore the statement is true

When I logically think about this situation I think it is false. I imagine myself driving down the highway in my stang turning 2500 rpm at 100 mph. Assume I stay in the same gear. Unless I raise the revs by giving it more gas I will not accelerate. When raising the engine rpm my engine makes more power...so how can I accelerate if my engine maintains a constant rpm(same power output)?
 
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Your equations are correct and so is your logic. However, can you think of any additional forces which may act against the acceleration of the car?
 
Ah, wind resistance and friction between the road and tires...and then there's also the some power loss due to the weight of the drive train components.
 
Yeah. I think it's funny to think about a bike. The wheels are so thin, but that little surface area combined with the air stops you from going as fast as you want.
 
so just that little bit of resistance from the tires and the air hitting the body of the car prevents the car from accelerating,correct?
 
so the answer would be true?
 
Yes, so it's not that little really.
 
jim_ringo said:
so the answer would be true?

Well in real life the answer is false for a car. A rocket in deep space could accelerate indefinitely.
 
jim_ringo said:
a cars engine produces constant power therefore the cars speed will increase at a constant acceleration.

is this true or false

Homework Equations


Power=w/t
work=fd
so P=mad/t

The Attempt at a Solution



so if p is constant it appears a must be constant. Therefore the statement is true
Whoa! I'm not convinced that you have demonstrated it to be true. All I see you having shown here is that
the factor (ad/t) is constant. I think you are asked to determine whether or not a is constant---am I correct in believing that is what the problem is asking?
 
  • #10
NascentOxygen said:
Whoa! I'm not convinced that you have demonstrated it to be true. All I see you having shown here is that
the factor (ad/t) is constant. I think you are asked to determine whether or not a is constant---am I correct in believing that is what the problem is asking?

Yes that is what the problem is asking
 

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