Calc Energy to Take 1,112kg Car 1.2km Up Mtn: 3SF

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SUMMARY

The energy required to elevate a 1,112 kg car to a height of 1.2 km is calculated using the potential energy formula PE = mgh. The correct calculation, using the more precise gravitational constant of 9.81 m/s², results in an energy value of 13,090,464 Joules, which can be expressed in scientific notation as 1.31E7 Joules. This value is rounded to three significant figures as required by the problem statement.

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  • Understanding of potential energy (PE) and kinetic energy (KE) concepts
  • Familiarity with the formula PE = mgh
  • Knowledge of significant figures in scientific calculations
  • Basic proficiency in unit conversion (e.g., kilometers to meters)
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Homework Statement


What is the energy needed to take a 1,112 kg car to 1.2 km up a mountain? Write your answer to 3 significant figures.


Homework Equations


PE = KE
PE = mgh
KE = ½mv2
mgh = ½mv2
1 km = 1000 m

The Attempt at a Solution


h = 1.2 km = 1200 m
PE = mgh = (1112)(9.8)(1200) = 13077120
PE = KE
Energy = 13077120 Joules

I don't think my answer is correct because it says to write my answer to 3 significant figures.
Where did I go wrong?
 
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dont forget...when dealing with large numbers its best to include as many sig figs in your calculations as possible, use 9.81 instead of 9.8 and you will get something that you can round to 1.31E7 J
 
SSJ2 said:
dont forget...when dealing with large numbers its best to include as many sig figs in your calculations as possible, use 9.81 instead of 9.8 and you will get something that you can round to 1.31E7 J

(1112)(9.81)(1200) = 13090464
13090464 = 1.31E7

Energy = 1.31E7 Joules

So, is that the answer?
 

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