A solid is formed by a pyramid mounted on a cube, the base coinciding with cube's upper face. Side of cube is 16 cm16cm and the apothem of the pyramid is 17 cm17cm. Calculate: the total surface area, the volume and mass knowing is made wood 0.65 g/(cm^3)0.65gcm3?

1 Answer
Jun 2, 2018

Total Surface Area: \ color(green)(T S A = "1824 cm"^2)

Volume: \ color(maroon)(V_t = V_c + V_p = "23296 cm"^3)

Mass of wood: \ color(blue)(m = d * V_t = 15,142.4 \ "g")

Explanation:

Side = a = "16 cm", apothem = l = "17 cm"

Total Surface Area = Base Area of Cube + Lateral Surface Area of the Cube + Surface Area of Pyramid

Base Area of Cube A_b = a^2 = "256 cm"^2

Lateral Surface Area of Cube A_c = 4 a^2 = "1024 cm"^2

Surface Area of Pyramid = A_p = 4 * (a/2) * l = 4 * 8 * 17 = "544 cm"^2

T S A = 256 + 1024 + 544 = "1824 cm"^2

"Total Volume" \ (V_t) = "Volume of Cube" \ (V_c) + "Volume of Pyramid" \ (V_p)

V_c = a^3 = 16^3 = "4096 cm"^3

V_p = (1/3) * a^2 * h = (1/3) * a^2 * sqrt(l^2 - (a/2)^2)

V_p = (1/3) * 16^2 * sqrt(17^2 - 8^2)

V_p = (1/3) * 256 * 225 = "19200 cm"^3

"Volume" \ V_t = V_c + V_p = 4096 + 19200 = "23296 cm"^3

Mass of Wood m = "density" * "volume"

m = d * V_t = 0.65 * 23296 = 15,142.4 "g"