Question

Плот состаит из 20 бревен сосны. Определите подъемную силу плота если плотность сосны 5100кг/м3 , плотность воды 1000 кг/м3 , объем одого бревна сосны 0,5 м3

Answer 1

F = P - FA 

P - вес 
FА - Архимедова сила 

P = m * g 

m - масса 
g - ускорение свободного падения ( 10 Н / кг ) 

m = p * V 

p - плотность ( для сосны 5100 кг / м³ ) 
V - объём ( 0,5 м³ * 20(так как брёвен 20 ) = 10 м³ ) 

m = 5100 * 10 = 51000 кг 

P = m * g = 51000 * 10 = 510000 H 

FA = p * g * V 

p - плотность жидкости ( для воды 1000 кг / м³ ) 
g - ускорение свободного падения ( 10 Н / кг )
V - объём тела ( 10 м³ ) 

FA = 1000 * 10 * 10 = 100000 H 

F = P - FA = 510000 - 100000 = 410000 H = 410 кН

Answer 2

Calculating the Buoyant Force on the Raft

To calculate the buoyant force on the raft, we can use the formula:

Buoyant force = Weight of the water displaced

The weight of the water displaced can be calculated using the formula:

Weight of the water displaced = Volume of water displaced × Density of water × Acceleration due to gravity

Given: - Density of pine wood (raft material) = 5100 kg/m^3 - Density of water = 1000 kg/m^3 - Volume of one pine wood log = 0.5 m^3

Let's calculate the buoyant force on the raft using the provided information.

Calculation

First, we need to find the weight of the water displaced by the raft. The weight of the water displaced is equal to the weight of the raft, which is equal to the weight of the pine wood logs.

The weight of one pine wood log can be calculated using the formula:

Weight of one pine wood log = Volume of one pine wood log × Density of pine wood × Acceleration due to gravity

Substituting the given values: Weight of one pine wood log = 0.5 m^3 × 5100 kg/m^3 × 9.81 m/s^2

Now, we can calculate the total weight of the raft by multiplying the weight of one pine wood log by the total number of logs in the raft.

Given: - Number of logs in the raft = 20

Total weight of the raft = Weight of one pine wood log × Number of logs in the raft

Finally, the buoyant force on the raft is equal to the weight of the water displaced, which is equal to the total weight of the raft.

Result

By calculating the total weight of the raft and using the principles of buoyancy, we can determine the buoyant force acting on the raft.