1. People working on the roofs of buildings often lay a plank of wood on the roof. They walk on the plank rather than the roof itself. a) Explain why using a plank will help to prevent damage to the roof.
b) A workman's weight is 850 N, and each of his boots has an area of 210 cm2. Calculate the maximum pressure under his feet when he is walking. Give your answer in pascals. c) The workman lays a plank on the roof. The plank has an area of 0.3 m2 and a weight of 70 N. What is the maximum pressure under the plank when he is walking on it?(1+2+2)