Calculating Average Power for a 1500kg Car Going from 0 to 90km/h in 5s

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SUMMARY

The discussion focuses on calculating the average power required for a 1500kg car to accelerate from 0 to 90km/h in 5 seconds. The correct approach involves determining acceleration and displacement rather than using gravitational force. The final calculation yields an average power of 93750 watts or 125.7 horsepower, derived from the formula P=Fv, where force is calculated using F=ma. Key steps include converting speed to meters per second and applying kinematic equations to find displacement.

PREREQUISITES
  • Understanding of Newton's Second Law (F=ma)
  • Knowledge of kinematic equations (Vf² - Vi² = 2aS)
  • Ability to convert units (km/h to m/s)
  • Familiarity with power calculations (P=Fv)
NEXT STEPS
  • Learn about kinematic equations in detail
  • Study unit conversions, specifically speed and force
  • Explore the relationship between power, force, and velocity
  • Investigate real-world applications of average power in automotive engineering
USEFUL FOR

This discussion is beneficial for physics students, automotive engineers, and anyone interested in understanding the principles of motion and power calculations in vehicles.

bob24
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Homework Statement


A 1500kg car can go from zero to 90km/h in 5.0 seconds. What is the average power required to do this?


Homework Equations



I tried with P=Fv, I don't really know what else to use(

The Attempt at a Solution


First I converted the 90km/h to m/s and got 25m/s/
Then I did F=mg with m=1500 and g=9.81m/s^2
Then I used the equation P=Fv
P=Fv
P=14175 x 25m/s
P=354375W

ANSWER: 93750w OR 125.7 hp.

Any help would be greatly appreciated.
Thanks
 
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bob24 said:


3. The attempt at a solution
First I converted the 90km/h to m/s and got 25m/s/


OK

Then I did F=mg with m=1500 and g=9.81m/s^2

You can't use g hare. Find the acceleration. And then the displacement.
 
rl.bhat said:
bob24 said:


3. The attempt at a solution
First I converted the 90km/h to m/s and got 25m/s/


OK

Then I did F=mg with m=1500 and g=9.81m/s^2

You can't use g hare. Find the acceleration. And then the displacement.


----
Ok I got acceleration=5m/s^2, and then I did Vf^2-Vi^2=2aS and got 62.5 meters for S.
So do I do
F=ma
F=1500 x 5
F=7500 N?
 
Now average power =ForceX average velocity
 
rl.bhat said:
Now average power =ForceX average velocity

Excellent. Thank you very much!
 

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