PART 1

Question

Raft made of 2.2m long pine logs with Average diameter of logs 26cm.How many logs are needed to strap together to build raft to hold max 4 people?
Density of log = 600 kg/m^3
Each people weights 512N

PART 2
What percent of the logs is under water when you are on your raft in the water with your friend?

Answer 1

find volume of each log.
Now, the bouyancy must equal the weight of logs + people.
Bouyancy=masslogs+masspeople
let n be number of logs.
let volume V of logs=2PI*.13^2
n*V*densitywater=n*V*densitylog+ 4*512

nV(densitywater-densitylog)=4*512
solve for n. If it is decimal number, round UP.