Question

why it is difficult to walk in lose sand and snow using shoes with the pointed heel

Answer 1

pressie is less and force is more

Answer 2

it is because of the pressure that is applied on by the pointed end of the heels,  if we wear shoes with pointed heels, the weight of our body falls on a small area, thereby producing a large pressure on sand ,so heels will tend to sink and make walking difficult on sand.