Solution: To require volume, you must know the bottom area and bottom radius. After sawing, the two rectangles are added together, so the area of a rectangle is 400 square centimeters. According to the area of a rectangle, it is equal to the length multiplied by the width, and the length is equal to the height of wood, so the width of a rectangle is 400 divided by 40, which is equal to 10 cm. The width of this rectangle is the diameter of the bottom circle and the radius is 5cm, so the bottom area = volume =78.5×40=3 140 (cubic centimeter).

Specific steps: 800÷2=400 (square centimeter)

400÷40= 10 (cm)

10/2 = 5cm

3. 14×5×5=78.5 (square centimeter)

78.5×40=3 140 (cubic centimeter)

A: It turns out that the volume of this piece of wood is 3 140 cubic centimeters.