i have knowledge in reading tonic solfa notation. 4/4, 6/8 etc. I also have knowledge in music and audio production with the use of computer softwares, e.g FL Studios. I wish to know about the length of a bar. And also, about meaaures. thank you...
The length of a bar isn't measured, musically, in any units like inches or millimetres! And really, musically, not measured in time units like seconds etc.
A bar is a convenient way to split up a tune. Most tunes have a rhythm running through them, which is repetitive. A pattern. We count through, and establish when the pattern repeats. Then we know how a bar must be represented.
Often, we count 1 2 3 4 1 2 3 4. So that song is said to be 'in 4'. We then need to decide how to subdivide that bar, and often it's into 4 crotchets. That gives us the bottom number. a little like fraction - 4/4.
If the count is 1 2 3 1 2 3 then it could be 3/4.
Now to the question - and answer. The speed, or tempo is dictated by how slowly or quickly we had to count 1 2 3 4 etc. These days, it's noted as b.p.m., which is beats per minute. So, at 60 bpm for those 4 crotchets in a bar, one bar will last 4 seconds. At 120bpm, it'll be 2 secs. What we don't do is use a stopwatch to time a bar - unless we're writing for cartoons, films, and so on!
You ask about measures. It's a synonym for bars.
A bar and a measure refer to the same thing, however, "measure" is used more in American English. The length of a bar depends on the time signature.
For example, if the time signature was
4/4 then the bar would be 4 crotchets (quarter notes) long. However, if the time signature was
6/8 then the bar would be 6 quavers (eighth notes) long.
The duration of the bar (in terms of time), is given by the bpm, such that the time of a bar is
60 * number of beats in a bar / bpm in seconds. E.g.
100 bpm in
4/4 would be
2.4 seconds per bar.
Addendum: Some musician distinquish a bar as the vertical line found in sheet music and the measure as the segment of time corresponding to a specific number of beats.