Say we have a BPM of 60. Does that mean each one of my whole notes is 1 second long? Because 60 beats per minute means I have 1 beat every second. (60/60 = 1)
Or if I have a BPM of 120, then each one of my whole notes is (60/120) = 0.5 seconds? Does this sound right?
If the tempo is 60 BPM then each beat is 1 second long. Normally, the whole note does not get the beat. The most popular note value to represent one beat is the quarter note. So if the quarter note gets the beat and the tempo is 60 BPM, then each quarter note lasts 1 second and each whole note lasts 4 seconds.
If the tempo is 120 BPM, and the quarter note gets the beat, then each quarter note is .5 seconds long and each whole note is 2 seconds long.
If the tempo is 60 BPM and the time signature is 6/8 (which means the eighth note gets the beat), then an eighth note lasts 1 second and a measure lasts 6 seconds which means that a whole rest might be six seconds long (since often whole rests indicate the entire measure no matter what), and some might use a whole note for the whole measure in which case that would also be a 6 second whole note.
Looking at 12/8 time with a tempo of 60 BPM, you could see whole rests and even whole notes that last for 12 seconds. It's also possible that the whole rests and/or notes in 12/8 time would only have a value of 8 eighth notes and be 8 seconds long, which means for an entire measure you would see a dotted whole note and less often a dotted whole rest.
What's more common for 6/8 and 12/8 time is that there will be a mark near the tempo that says that the dotted quarter note gets the beat. It might be dotted quarter note followed by "= 60 BPM". In that case, a 6/8 measure has two beats in it that each last 1 second, and a whole note would be two seconds long, and a 12/8 measure would have four beats that each last one second, and a whole note would be four seconds long. Also in those cases, an eighth note would last .333... seconds long, or 1/3 of a second.
A whole note (semibreve in U.K ) lasts the whole bar in 4/4 time. Generally it's not known as a beat. That is usually down to the crotchet, or quarter note. So, in a whole bar (measure) in 4/4, a beat is a quarter of that bar.
Thus, in 4/4, with 60bpm (beats per minute), one bar will last for exactly four seconds. In reality, no-one will time a bar while playing in that manner - it's hardly practical - but would set a metronome to 60bpm., and work so that each click represents one beat, or here, one crotchet (quarter note).
Looking at your example, if the bpm is 120, then in a piece in 4/4, each beat working as crotchets, would last for 1/2 a second. Thus the whole bar would now take two seconds to perform. However, as remarked upon earlier, would one expect a performer to work with a stopwatch, and check each note for duration? It'd be a new one on me, at least...
