It's about 70,000,000 times as fast as Grass growing.
In other words, the speed of Grass growing is 0.0000000140 times 0.0084 mach.(for Kentucky Bluegrass, Poa pratensis) (a.k.a. Smooth Meadow grass, a.k.a. Common Meadow grass) (Summer months, ideal growing conditions)
Kentucky Bluegrass, one of the most common grasses in North America, grows about 0.000000000130 mach in the summer months under ideal conditions. When left un-mowed, Kentucky Bluegrass grows to heights of 60 to 90 cm (2 to 3 ft) and blossoms with a blue flower.
It's about 40 times as fast as a Sloth.
In other words, 0.0084 mach is 42 times the speed of a Sloth, and the speed of a Sloth is 0.024 times that amount.(for Brown-throated three-toed sloth, Bradypus variegatus)
The three-toed sloth moves along the ground at an average speed of 0.0002 mach. Long thought to be lengthy sleepers, a 2008 study concluded that sloths sleep an average of only 9.6 hours per day.
It's about six times as fast as an Iceberg.
In other words, the speed of an Iceberg is 0.20 times 0.0084 mach.(a.k.a. Berg) (Newfoundland iceberg average)
Moved by ocean currents and wind, icebergs can drift at speeds of about 0.002 mach. The largest iceberg ever recorded was a found near Baffin Island, Nunavut and was estimated to be nine billion metric tons.
It's about two times as fast as Walking Pedestrians (in Manhattan).
In other words, 0.0084 mach is 2.10 times the speed of Walking Pedestrians (in Manhattan), and the speed of Walking Pedestrians (in Manhattan) is 0.480 times that amount.(Manhattan; average speed; 8,978 person-sample)
A 2006 Study by the New York City Department of City Planning found that pedestrians in that city walk at an average rate of 0.0039 mach. Pedestrians wearing headphones, the study went on to find, walk at a slightly faster 0.0043 mach
It's about one-and-two-fifths times as fast as Michael Phelps.
In other words, 0.0084 mach is 1.43370 times the speed of Michael Phelps, and the speed of Michael Phelps is 0.69750 times that amount.(at the Beijing Olympics, 2008; 200 m freestyle) (a.k.a. Michael Fred Phelps) (swimmer; 1985-)
Setting a world record, Michael Phelps swam the 200 m freestyle in 1:42.96 for an average speed of 0.0058588 mach. Phelps would go on to win nine gold medals individually in the 2008 Olympics - more than all but eight of the competing nations.
It's about as fast as a Crocodile.
It's about two-fifths as fast as a Bull.
In other words, 0.0084 mach is 0.420 times the speed of a Bull, and the speed of a Bull is 2.40 times that amount.(for animals involved in the Running of the Bulls, a.k.a. Encierro, San Fermin, Pamplona, Spain) (herd average speed)
The herd of the annual Encierro in Pamplona, Spain runs at an average speed of 0.02 mach. The Encierro is run annually from July 7th through July 14th and involves 42 bulls, 77 oxen, and an estimated 17,000 runners over the course of the event.