First, a single coefficient A was used to denote what should have been three separate proportionality constants. Three distinct uses of A were:
A1: Efreq=A(g/V)k, used in Eqn 1, with units of J sk,
A2: Efreq=Afk, used in the list of symbols and in the caption to Fig. 4, also with units of J sk,
A3: , used in Appendix 2, and in Eqns 3 and A15, with units of .
For impulsive running, A2=2kA1. By setting k=2, taking the derivative of Eqn 1 with respect to V and setting to zero, we can solve for A3 in terms of A1, and find A3=(2A1/m)1/4, for A1 at k=2.
Second, a missing exponent in the code generating Fig. 4 led to improperly scaled axes. Although each axis should be down-scaled, the relative shape of the curves is unchanged in the corrected figure (see below). The optimal take-off velocities in the corrected figure correspond approximately to those of the best fit in Fig. 2B for each level of gravity.
The premise and conclusions of the paper are unchanged. The authors would like to thank the reader who brought these errors to their attention.
The authors apologise for any inconvenience this may have caused.