Find Distance of Car, given Rest-Energy

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Homework Help Overview

The problem involves calculating the distance a car could travel using the energy derived from an aspirin tablet, given the energy output of gasoline and the mass of the aspirin. The subject area encompasses energy conversion and basic physics principles related to mass-energy equivalence.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to convert the mass of aspirin into energy using the rest energy formula, E=mc², and then relates this energy to the distance a car can travel based on the energy provided by gasoline. Some participants question the validity of the calculations and the assumptions made regarding energy conversion.

Discussion Status

Participants are exploring the calculations and discussing the implications of the results. There is a mix of agreement and skepticism regarding the accuracy of the original poster's calculations and the feasibility of the conclusions drawn from them.

Contextual Notes

There appears to be confusion regarding unit conversions and the practical implications of the results, with some participants expressing disbelief at the calculated distance. The discussion highlights the need for clarity in assumptions about energy conversion and measurement units.

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Homework Statement


Suppose one gallon of gasoline produces 1.01×108 J of energy, and this energy is sufficient to operate a car for 18.2 miles. An aspirin tablet has a mass of 332 mg. If the aspirin could be converted completely into thermal energy, how many miles could the car go on a single tablet?

Homework Equations





The Attempt at a Solution



1 gallon of gas= (1.01E8) J
Distance of car(on gas)= 18.2 miles
Mass(aspirin)= 332 mg
Looking for
Distance of car(on asprin)=?


I converted the mass from grams to kilograms.
332mg = (332E-3)g = (332E-6)kg

*After this I'm not sure if I'm doing the right thing.*
The problem says "converted completely into thermal energy" so I'm assuming that this means I need to find the rest energy.
Erest=mc^2 [m=mass in kg; c=speed of light=(3E8)m/s]
=(332E-6)(3E8)^2
=(332E-6)(9E16)
=(2.988E13) J​

I then set up the energy of gas, distance on gas and the energy I found abvoe of the asprin, to solve for distance on asprin?
(distance of gas)/(energy of gas)=(distance of aspirin)/(energy of aspirin)
=(18.2 miles)/((1.01E8)J)=(?distace of asprin?)/((2.988E13)J)
=[(18.2)(2.988E13)]/(1.01E8)
=(5.43816E14)/(1.01E8)
=5384316.832 miles = (5.38E6) miles​

However that answer is incorrect and I'm not sure if I am even using the right formulas for this problem.

Any help would be greatly appreciated!
 
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is the answer 0.001242742 miles?
im not a guru btw
 
The correct answer is (5.38E6)mi. My calculations were correct, I just had my units of measurement wrong.
 
Hi blue_lilly. I'm pleased that the physics forums was able to help you to solve your problem on this occasion. :smile:
 
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errr so a gallon of gas get you 18 miles and an aspirin 5.38*10^6 miles ?

i guess we been using the wrong fuel all this time...
 
Patolord said:
errr so a gallon of gas get you 18 miles and an aspirin 5.38*10^6 miles ?

i guess we been using the wrong fuel all this time...

If only it really worked like that, we would saving a lot of money. C:
 

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