Finding Force then converting to work

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SUMMARY

The discussion focuses on calculating the average and instantaneous power developed by a car engine during acceleration. The car, weighing 1.50 x 103 kg, accelerates to 19.3 m/s over 11.6 seconds, with a constant air resistance of 400 N. The user initially calculated the work done as 279367.4267 J but was informed that this value only represents work, not power. The correct approach requires dividing the work by time to find average power and using instantaneous force for instantaneous power calculations.

PREREQUISITES
  • Understanding of Newton's Second Law (F=ma)
  • Familiarity with kinematic equations
  • Knowledge of power calculations (P=W/t)
  • Basic concepts of work and energy in physics
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  • Learn how to apply kinematic equations for different motion scenarios
  • Explore the concept of instantaneous power and its calculation
  • Review examples of forces acting on objects in motion, including friction and air resistance
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Students studying physics, particularly those focusing on mechanics and dynamics, as well as educators seeking to clarify concepts of work and power in real-world applications.

cjknowland
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Homework Statement



A 1.50 x 10^3 kg car starts from rest and accelerates uniformly to 19.3 m/s in 11.6 s. Assume that air resistance remains constant at 400 N during this time.

(a) Find the average power developed by the engine.

(b) Find the instantaneous power output of the engine at t = 11.6 s, just before the car stops accelerating.

Homework Equations



W=F(Δx)
F=ma

The Attempt at a Solution



I used kinematic equations to find the Δx at 111.94 and a at 1.663 m/s. (may want to check)

I then used F=ma to find F = 2495.689

then multiplied F by Δx to get 279367.4267 for Work but I am told by my homework website that I am off by a multiple of ten. I can easily guess for the answer but I want to know where I went wrong...

thank you
 
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I do not think there is any mistake in your work. But you were asked for the POWER and you found ONLY the work done up to now.
 

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