Find the Power to move a car on an incline

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SUMMARY

The power required to move a 3000 lb car up an 8-degree incline at a constant speed of 50 mi/h against a frictionless force of 80 lb is calculated to be 68 horsepower. The calculation utilizes the formula P = Fv, where the force includes both the gravitational component and the frictional force. The final result confirms that the power needed is approximately 66.34 horsepower, aligning with the established calculations presented in the discussion.

PREREQUISITES
  • Understanding of basic physics concepts, specifically forces and power calculations.
  • Familiarity with the formula P = Fv for calculating power.
  • Knowledge of unit conversions, particularly between miles per hour and feet per second.
  • Ability to interpret free body diagrams for analyzing forces acting on an object.
NEXT STEPS
  • Study the principles of inclined plane mechanics and their applications in physics.
  • Learn more about unit conversions, particularly in the context of speed and force.
  • Explore advanced power calculations in physics, including potential energy changes.
  • Investigate the effects of friction and other forces on motion in various scenarios.
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Students studying physics, engineers working on automotive design, and anyone interested in understanding the mechanics of moving objects on inclines.

BSElectrician
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Homework Statement


What power is needed to move a 3000lb car up an 8 degree incline with a constant speed of 50mi/h against a frictionless force of 80lb?

ans. 68hp

Homework Equations



P = Fv

1hp = 550 lb-ft/s

The Attempt at a Solution


1st i draw free body diagram
summation of force in the horizontal direction
Fx = 0 = 3000sin(8) + 80 - Fn
Fn = 497.52lb

Power = velocity x force
= (50mi/h)(1/3600s)(1ft/0.3048m)(1000m/1km)(1km/0.62137mi)
= 36,485.56 lb-ft/s
= (36,485.56 lb-ft/s)(1hp/(550lb-ft/s))
= 66.34 horsepower
where did i get wronged?
 
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I get the same answer you have.
 
I think your answer is correct. I get the same result either by figuring the forces and multiplying by velocity (as you did) or by using the 80 pound force times velocity added to the change in potential energy per second.
 

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