20 lengths of a 25 meter pool, or 10 lengths of a 50 meter pool. Some people refer to a lap as one pool length, while others refer to a lap as down and back (2 lengths). I haven't found which one is the correct terminology, but the term length has only one meaning (for the particular pool that you are using).
500m
Swimmers may change between their race and practice suits at competitions because wearing the racing suit for long periods of time can be really uncomfortable. They tend to be more form fitting and some swimmers will go down a few sizes in their race suit, making it even tighter.
Soviet speed skater Yevgeny Grichin won the gold in the 500m race in the 1956 Winter Olympics.
There is no right answer to your question. there can be 5, 2, or 12.
is it 500 blocks
The backstroke.
8
yes there are touch pads in the olympic swimming pools that the swimmers have to touch to win the race.
Permanent markets like Sharpies.
"Free"style of course
It will take 50 seconds for a man running at 10m per second to travel 500m. This is calculated by dividing the distance (500m) by the speed (10m/s).
for swimming there is a meet called Olympic trials to reach that point there are tie standards you must reach. From that point the swimmers swim once in prelims where the top 16 move on to semi finals once the swimmers swim here the Field narrows even more down to 8 swimmers finally the swimmers swim one last race in the finals the top two swimmers in that race go to the Olympics