A raft is made using a number of logs (TBD) with 25-cm diameter and 2-m-length. It is desired that a maximum 90 percent volume of each log will be submerged when carrying two boys with 400 N each. Determine the minimum number of logs that must be used. The specific gravity of the log is 0.75.

Respuesta :

Answer:

6logs

Explanation:f

First finding the volume of the logs

V= π/4d²l

= 0.098m³

So number of logs will be

Weight of 2 boys + weight of log = buoyancy force.

So

2( 400)+ N ( Mlog x g) = density of water x volume displaced x g

2(400) = N x 0.098x 1000x 9.8 x 0.9- 0.75* 1000

N= 5.5 which is approx 6logs

The minimum number of logs that must be used is 6 logs.

Calculation of the number of logs:

Here first determine the volume of the logs i.e.

V= π/4d²l

= 0.098m³

Now

number of logs will be

Weight of 2 boys + weight of log = buoyancy force.

2( 400)+ N ( Mlog x g) = density of water x volume displaced x g

2(400) = N x 0.098x 1000x 9.8 x 0.9- 0.75* 1000

N= 5.5

= 6logs

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