Drag Racing - Involving Work and Velocity

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SUMMARY

The discussion focuses on a physics problem involving two identical cars accelerating from rest at different rates and then decelerating. The first car accelerates to 20 mph while the second reaches 40 mph, both covering the same distance in 30 seconds. Key equations include acceleration defined as change in velocity over time and work calculated as force multiplied by distance. The problem requires calculating the work done by each car's engine and brakes, emphasizing the importance of energy formulas such as kinetic energy (KE = ½mv²).

PREREQUISITES
  • Understanding of basic physics concepts such as acceleration and work
  • Familiarity with kinetic energy calculations
  • Ability to convert units, specifically from imperial to metric
  • Knowledge of motion equations and their applications
NEXT STEPS
  • Study the principles of acceleration and deceleration in physics
  • Learn how to apply kinetic energy formulas in practical scenarios
  • Explore the concept of work-energy theorem in physics
  • Investigate the effects of friction on motion and energy calculations
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the dynamics of motion and energy in automotive contexts.

marcus1255
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Homework Statement



The problem reads:

"You are stopped at a red light, an identical car to yours pull up alongside. When the light turns green, you and the other car accelerate at a constant rate, but the other car's acceleration is greater. You see another stop light ahead and know you will have to stop at the light, so you accelerate from 0 to 20 mph for half the distance and then brake slowly so you decelerate for the last half, you observe this takes you a total of 30 seconds. The other car accelerates from 0 to 40 mph for the first half of the distance and brakes for the last half. Both cars traveled the same distance, starting from rest and ending at rest. You want to know how much work your car engine did compared to the other car and how much work your brakes did compared to the other car"

Homework Equations



Acceleration = change in velocity / change in time
Work = Force x Distance


The Attempt at a Solution



I am not really sure where to start..
 
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Convert to metric units. Do the motions one at a time, beginning with the acceleration from 0 to 20. There evidently is no friction loss, so you can just use energy formulas like KE = ½mv².
 

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