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

Explanation

When a man walks bare footed on sand, the sand yields under the weight of the man. The man does not get proper reaction from sand which is necessary for his walking. This difficulty can be overcome by spreading the wooden board on the sand. In this situation, the thrust on the sand due to our weight will get spread over the whole area of the board and hence a very small pressure is exerted on the sand . Due to it, the sand does not yield.