Calculating Power for a Coasting Car with Given Equation and Values | 1072 kg

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SUMMARY

The discussion focuses on calculating the power required for a 1072 kg car coasting at a speed of 18.05 m/s after 38 seconds, using the equation v(t) = a − bt + ct², where a = 26.8 m/s, b = 0.310 m/s², and c = 2.10·10^-3 m/s². To solve the problem, participants suggest applying Newton's second law to determine the force acting on the car and then using the power equation to maintain the constant velocity against air and rolling resistance. The discussion emphasizes the importance of recognizing the car's constant velocity after the initial deceleration.

PREREQUISITES
  • Understanding of Newton's second law of motion
  • Familiarity with the equations of motion
  • Knowledge of power calculations in physics
  • Basic concepts of air resistance and rolling resistance
NEXT STEPS
  • Review the derivation of Newton's second law and its applications
  • Study the equations of motion for uniformly accelerated motion
  • Learn how to calculate power in mechanical systems
  • Investigate the effects of air resistance and rolling resistance on vehicle dynamics
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This discussion is beneficial for physics students, automotive engineers, and anyone interested in understanding vehicle dynamics and power calculations related to motion and resistance forces.

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A car with a mass of 1072 kg is coasting in neutral on a straight,level road. It slows down, and its speed as a function of time is given by the equation:
v(t) = a − bt + ct2



Constant Value Units
a 26.8 m/s
b 0.310 m/s2
c 2.10·10^-3 m/s2

At a time of 38.0 s the speed, as given by the above equation, is 18.05 m/s. Calculate the power which the engine must deliver (to compensate for air resistance and rolling resistance) in order to maintain that speed.

This is the problem; but I couldn't solve it. Please help.
 
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Have you made an attempt at a solution (per Forum rules)? Try using Newton's second law to find the force acting on the car after 38 seconds, then recognize that the car moves at constant velocity thereafter , and use the equation for power required to maintain that speed. Please list the relevant equations. And welcome to PF!:smile:
 

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