Heat and Kinetic Energy Question

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SUMMARY

The discussion centers on calculating the increase in temperature of wrecked cars after a collision, where both cars travel at 90 km/hr. The specific heat capacity (c) is given as 447 joules/kelvin. The initial calculation of kinetic energy was determined to be 625 joules per car, leading to a temperature increase of 1.4 K when divided by the specific heat capacity. However, participants noted that the total heat should account for the combined mass of both cars, indicating a need for a revised calculation.

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  • Understanding of kinetic energy calculations
  • Familiarity with the specific heat capacity concept
  • Knowledge of the formula Q = mc(change in T)
  • Basic principles of thermodynamics
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a_narain
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Homework Statement


Two cars collide as both are traveling at 90km/hr. What is the increase in temperature of the wrecks, assuming that the cars have c = 447 joules/kelvin.


Homework Equations


Q= mc(change in T)


The Attempt at a Solution


I found the joules of kinetic energy equal to 625 joules * mass of car (25 m/s speed = 625/2 joules of KE per car X two cars).
I then divided that by 447 for the c value, to get 1.4 K. But the answer is not correct?
 
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a_narain said:

Homework Statement


Two cars collide as both are traveling at 90km/hr. What is the increase in temperature of the wrecks, assuming that the cars have c = 447 joules/kelvin.

Homework Equations


Q= mc(change in T)

The Attempt at a Solution


I found the joules of kinetic energy equal to 625 joules * mass of car (25 m/s speed = 625/2 joules of KE per car X two cars).
I then divided that by 447 for the c value, to get 1.4 K. But the answer is not correct?

Half of that would be correct though wouldn't it?

Don't you have to consider the total heat into the total mass?
 

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