My daughter dived underwater in the swimming pool and screamed as loud as she could. I was right next to her with my head out of the water, but I could only detect the tiniest sound, at the end of the scream. But when I was underwater with her, I could hear most of the scream. Why?

I visited the local swimming pool today with my sisters. The majority of the time I was kneeling on the floor of the pool and supervising them. When I was in the pool I didn't feel as though I was doing much (if any) exercise, though on the way home I felt as though I'd done a lot more than usual. My muscles didn't ache but I felt very drained of evergy and rather hungry.

Can anyone explain why this happened?

Thanks in advance.

However tight I fasten my swimming goggles they always end up round my neck after I dive in. This never seems to happen to Olympic swimmers. Why not?

Francis Melo, Birmingham, UK

Easy enough for runners or other load bearing exercises.  But in swimming (and I suppose other activities) there are many variables.  Is it possible to come up with a meaningful average given:

• the mass of the swimmer
• the speed of the swimmer; and
• the resistance of the water, which will vary depending on

1. how much of the swimming stroke is out of the water and in the air (arm recovery and also stroke dependent, i.e breaststroke, butterfly, etc);
2. the streamlining efficiency of the swimmer, which will affect the resistance of the water
3. how long a swimmer can maintain a given efficiency (tiredness during the hour will impair the ability to stay efficient)
4. the temperature of the water