Question

Raft made of 2.2m long pine logs.Average diameter of logs 26cm.How many logs are needed to strap together to build raft to hold max 4 ?What percent of the logs is under water when you are on your raft in the water with your friend?

Answer 1

Please type entire problem.
Without knowing the density of the logs or the mass of you and your friend, no way.

call log density rho
call g = 9.81 m/s^2
water density = 1000 kg/m^2
mass of passengers = m
n = number of logs
n * .13^2 *2.2 = V, needed volume of logs
1000 g V = B = buoyancy force of logs fully submerged

floats when
B = m + rho g V

Answer 2

Density of logs is 600 kg/m^3 and weight is 512N for each