# Physics

posted by kely

PART 1
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?

1. bobpursley

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.

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