Answer :
The amount eroded at millimetre per hour is 0.002283
In order to determine the answer, take the following steps :
1. determine how many hours are in a year
there are 24 hours in a day
There are 365 days in a year
Number of hours in a year = number of days in a year x number of hours in a day
24 x 365 = 8760 hours
2. convert centimetre to millimetre
1 cm = 10mm
2cm x 10 = 20mm
3. Amount eroded per hour in millimetres = amount eroded per year / total number of hours in a year
20 / 8760 = 0.002283 millimetre / hour
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