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)

Asquare 1m x 1m plate is shown below. all four of its edges are kept at 0 co. at t=0the temperature distribution is given by: y xtsins n75)=.a) using separation of variables determine the temperature distribution t(x,y,t)along the plate at any time t.b) discretize the heat conduction equation +=22222 txtusing a second-order centered difference scheme for the two second derivatives and a first-order forward euler scheme for the first derivative. using von neumann stability analysis, determine the stability criterion for the proposed discretization scheme in terms of , hand t. solve for the maximum allowable time step tmax