Explain reasons of below mentioned

1. Our body experience high amount of atmospheric pressure, still our body does not get puckered. 

2. Why are strips of the school bags made thicker and broad. 

3. Tyres of heavy vehicles Eire made very thick 

4. Divers wear a metal armor while diving in sea.

क्या कैलोरियों की उचित मात्रा होने से भोजन सन्तुलित होता है?