
Step-by-step explanation:
2a. The block of wood has the shape of a rectangular prism. Â The log has the shape of a cylinder.
2b. Density is mass divided by volume. Â We know the mass, but we need to find the volume.
Volume of a rectangular prism is:
V = whl
where w is the width, h is the height, and l is the length
V = (18)(10)(8)
V = 1440 in³
So the density is:
d = 46.65 lbs / 1440 in³
d = 0.0324 lb/in³
2c. Â Volume of a cylinder is:
V = πr²h
where r is radius and h is height.
The circumference is C = 2Ï€r, so r = C / (2Ï€).
r = 25.12 / (2*3.14)
r = 4.00
V = 3.14 (4.00)² (21)
V = 1055.04 in³
So the density is:
d = 39.25 lb / 1055.04 in³
d = 0.0372 lb/in³
2d. Â The block is less dense than water; the log is more dense than water. Â So he should make the boat out of the block.