Amplitude is the pair of vertical buttons, so to speak. Compressions are the bunched up vertical lines with the purple arrows pointing left and right. Rarefactions are purple arrows pointing down. Wavelength is crest to crest purple buttons. Associated LH and RH pointing arrows.
The average dissipated power in a resistor in a ac circuit is:

where R is the resistance, and

is the root mean square current, defined as

where

is the peak value of the current. Substituting the second formula into the first one, we find

and if we re-arrange this formula and use the data of the problem, we can find the value of the peak current I0:
W=mgh W=(20)(9.8)(1) w=196J