Fixed error in SI table.

content/mechanicsintroduction.md

@@ -19,7 +19,8 @@ In physics in general, we are interested in relating different *physical quantit
 | :--- | :--: | :--- | :--: | :--- |
 | length | $L$ | meter | $\mathrm{m}$ | speed of light|
 | time | $T$ | second | $\mathrm{s}$ | caesium atom oscillation|
-| mass | $M$ | kilogram | $\mathrm{kg}$ | Planck's constant\\ current | $I$ | Amp|egrave;re | $\mathrm{A}$ | electron charge|
+| mass | $M$ | kilogram | $\mathrm{kg}$ | Planck's constant |
+| current | $I$ | Amp|egrave;re | $\mathrm{A}$ | electron charge|
 | temperature | $T$ | Kelvin | $\mathrm{K}$ | Boltzmann's constant|
 | luminosity | $J$ | candela | $\mathrm{cd}$ | monochromatic radiation|
 | particle count | $N$ | mole | $\mathrm{mol}$ | Avogadro's constant|