Calculating Average Power for Accelerating Car

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Homework Help Overview

The discussion revolves around calculating the average power required to accelerate a car from rest to a specified velocity over a given time period. The subject area is physics, specifically focusing on concepts of power, energy, and kinematics.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to understand how to apply formulas related to power and kinetic energy to solve the problem. They express uncertainty about the starting point and the relevance of time in their calculations. Other participants suggest using the kinetic energy formula and discuss the implications of the time factor in determining average power.

Discussion Status

Participants are actively engaging with the problem, with some providing formulas and calculations. There is a recognition of the importance of time in the context of average power, and while some guidance has been offered, there is no explicit consensus on the final approach or answer.

Contextual Notes

The original poster is preparing for an online certification and is seeking clarification on the problem, indicating a potential constraint of time and the need for understanding before the assessment.

PhysicsNovice
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Hello Everyone. I am almost through my on-line coarse on Introductory Physics. I am taking my last self-assessment before the on-line certification in two weeks. There is just one problem that has my confused. Please provide some guidance. Thanks.

Accelerating Car - What is the average power required to accelerate a 1200 kg car from rest to a velocity of 20 m/s in 10 seconds?

I am not even sure exactly where to start. I know that power can be measured in joules/sec a metric unit known as a watt. I do know some related formulas that might apply. They include:

Power = Change in Energy/Change in time
F = ma
W = Fd

I am still unclear how to proceed to determine that answer to this question in watts. :eek:
 
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You have another:
KE=1/2mv^2.
 
How appropriate. If anyone can help me it is the master of falling (accelerating) bodies...Galileo. Anyway, I am still confused on why your formula is the one I should start with. Can you explain? If I do use this formula I get:

KE=(1/2)(1200kg)(20m/s)^2
KE=(.5)(1200)(400)
KE=240,000

Now, is this watts? Also, is it important to consider the 10 second time in calculating the avergae power? If so then maybe the answer should be 240,000/10=24,000 watts. What do you think? I am on tract? Thanks.
 
Looks good to me :approve:

The car is started at rest, so it had no kinetic energy.
After 10 seconds it had 240,000 J of kinetic energy.

So it gained 24.000 J per second on average.
 

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