It si diffecult for a man to walk bare footed on sand. Why ? How can this difficulty be removed?

It is difficult for a man to walk on sand why?

It is difficult to walk on sand than on concrete road. Why?

What is the difficulty encountered in performing ring test wich lead nitrate ? How can this difficulty be overcome ?

What is astigmatism ? How can it be removed ?

Why is it difficult to walk on sand?

Why is it difficult to walk on sand?