A hummingbird’s heart can beat up to \(1200\) times per minute during flight. A “beat” in this context means one full cycle of the heart contracting and relaxing. When a quantity repeats regularly over time, scientists often describe it using a frequency (the number of repetitions per unit time). Biological frequencies are sometimes expressed in hertz, which in this context means beats per second.
Convert \(1200\) beats per minute into hertz. The common symbol for hertz is \(\text{Hz}\text{.}\)
Useful conversion factors:
\(1\, \text{Hz} = 1\, \frac{1}{\text{s}}\)
\(20\, \text{Hz}\)
Correct!
\(1200\, \text{Hz}\)
Your targeting system glitched, try again. It looks like you converted the units but forgot to divide by the number of seconds in a minute. You probably used \(1\,\text{min} = 1\,\text{s}\) instead of \(60\,\text{s}\text{.}\)
\(0.2\, \text{Hz}\)
Your enchanted click missed the mark, try again. It looks like you used the right conversion factor but inverted it, dividing when you should have multiplied. You probably calculated \(1200 \div 60 \div 100\) or something similar.
\(50\, \text{Hz}\)
Your digital blade missed the mark, try again. It looks like you divided by something close to \(24\) or \(25\) instead of by \(60\text{.}\) You may have confused minutes with hours or mixed up the direction of the conversion.
Checkpoint5.3.2.
An Olympic-sized swimming pool holds about \(2.5 \times 10^{6}\, \text{L}\) of water, where \(\text{L}\) is the symbol for liter. Many engineering specifications in the United States use gallons instead of liters. Convert \(2.5 \times 10^{6}\, \text{L}\) into gallons. The common symbol for gallons is \(\text{gal}\text{.}\)
Useful conversion factor:
\(1\, \text{L} = 1000\, \text{m}^3\)
\(1\, \text{m}^3 = 264.172\, \text{gal}\)
\(6.6 \times 10^{5}\, \text{gal}\)
Correct!
\(9.5 \times 10^{5}\, \text{gal}\)
Your targeting system glitched, try again. It looks like you inverted the liters-to-cubic-meters conversion. Instead of multiplying by \(1000\text{,}\) you probably divided by it.
\(4.0 \times 10^{5}\, \text{gal}\)
Your enchanted click missed the mark, try again. It looks like you performed both conversion steps correctly but rounded the \(264.172\,\text{gal}\) per cubic meter conversion factor too aggressively.
\(1.0 \times 10^{6}\, \text{gal}\)
Your digital blade missed the mark, try again. It looks like you multiplied by \(1000\) correctly but then mistakenly multiplied again when converting cubic meters to gallons rather than using the given factor once.
Checkpoint5.3.3.
The peregrine falcon is the fastest animal on Earth, capable of reaching diving speeds of about \(190\) miles per hour, or \(\text{mph}\text{.}\) Engineers often convert speeds into feet per second when analyzing motion, impacts, or aerodynamics. Convert \(190\, \text{mph}\) into feet per second.
Useful conversion factors:
\(1\, \text{mile} = 5280\, \text{ft}\)
\(280\, \text{ft/s}\)
Correct!
\(17000\, \text{ft/s}\)
Your targeting system glitched, try again. It looks like you converted miles to feet correctly and hours to minutes correctly but forgot to convert minutes to seconds.
\(130\,\text{ft/s}\)
Your enchanted click missed the mark, try again. It looks like you used the right conversion factors for miles to feet and hours to seconds but inverted both of them divided when should have multiplied and multiplied when should have divided.
\(1.0 \times 10^6\, \text{ft/s}\)
Your digital blade missed the mark, try again. It looks like you converted miles to feet correctly but forgot to convert hours to seconds.
