Q4. The picnic table has a weight 20kg with the Centre of gravity at GT. If a man weighing 80kg has a centre of gravity at GM and sits down in the centred position shown, determine the vertical reaction at each of the two legs at B. Ignore the thickness of the legs. Consider the following distances: a = 2cm, b = c = 10cm. What happens to the reaction force if a = 3cm? What does the sign indicate