What is the meaning of negative exponents in SI units?












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Please could someone explain the reason for using negative superscripts in SI units, and more precisely when to use negative versus positive?



I do not understand, for example, why the volume of a fuel would be given in m3 but heat of combustion would be given in J m-3.






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    1














    Please could someone explain the reason for using negative superscripts in SI units, and more precisely when to use negative versus positive?



    I do not understand, for example, why the volume of a fuel would be given in m3 but heat of combustion would be given in J m-3.






    mechanical-engineering







    share|improve this question







    New contributor




    tsvallender is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.























      1












      1








      1







      Please could someone explain the reason for using negative superscripts in SI units, and more precisely when to use negative versus positive?



      I do not understand, for example, why the volume of a fuel would be given in m3 but heat of combustion would be given in J m-3.






      mechanical-engineering







      share|improve this question







      New contributor




      tsvallender is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      Please could someone explain the reason for using negative superscripts in SI units, and more precisely when to use negative versus positive?



      I do not understand, for example, why the volume of a fuel would be given in m3 but heat of combustion would be given in J m-3.






      mechanical-engineering




      mechanical-engineering






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      tsvallender is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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          Negative exponents means per. In countries that were heavily influenced by the British, units such as meters per second would most likely be written $m/s$. In Europe and elsewhere it could be written with negative exponents as $m.s^{-1}$.



          In your example $J m^{-3}$ means joules per cubic meter.






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            Negative exponents means per. In countries that were heavily influenced by the British, units such as meters per second would most likely be written $m/s$. In Europe and elsewhere it could be written with negative exponents as $m.s^{-1}$.



            In your example $J m^{-3}$ means joules per cubic meter.






            share|improve this answer


























              3














              Negative exponents means per. In countries that were heavily influenced by the British, units such as meters per second would most likely be written $m/s$. In Europe and elsewhere it could be written with negative exponents as $m.s^{-1}$.



              In your example $J m^{-3}$ means joules per cubic meter.






              share|improve this answer
























                3












                3








                3






                Negative exponents means per. In countries that were heavily influenced by the British, units such as meters per second would most likely be written $m/s$. In Europe and elsewhere it could be written with negative exponents as $m.s^{-1}$.



                In your example $J m^{-3}$ means joules per cubic meter.






                share|improve this answer












                Negative exponents means per. In countries that were heavily influenced by the British, units such as meters per second would most likely be written $m/s$. In Europe and elsewhere it could be written with negative exponents as $m.s^{-1}$.



                In your example $J m^{-3}$ means joules per cubic meter.







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 4 hours ago









                Fred

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