Question

После непродолжительного торнадо Деревянное бревно оказалось в бассейне. Оно плавало в воде так, что 40 % его объема оставалось на поверхности воды. определите плотность дерева если плотность воды 1000 кг/м^3

Answer 1

Объем погруженной части 0,6*V
По условию плавания тел m*g=Fa
m=p*V
Fa=pж*0,6*V*g
p*V=pж*0,6*V*g p=1000*0,6=600 кг/м3

Answer 2

Calculation of Wood Density

To determine the density of the wood, we can use the principle of buoyancy. According to Archimedes' principle, the buoyant force acting on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. In this case, the buoyant force acting on the wooden log is equal to the weight of the water displaced by the log.

Given that 40% of the log's volume remains above the water surface, we can assume that 60% of the log's volume is submerged in water. Therefore, the buoyant force acting on the log is equal to 60% of its weight.

To calculate the density of the wood, we need to know the mass of the log and its volume. Since we have the percentage of the log's volume that is submerged, we can calculate the volume of the log using the submerged volume and the density of water.

Let's assume the mass of the log is m kg and the volume of the log is V m^3. The density of water is given as 1000 kg/m^3.

The buoyant force acting on the log is equal to the weight of the water displaced by the log, which can be calculated as:

Buoyant force = Weight of water displaced = Density of water * Volume of water displaced

Since the buoyant force is equal to 60% of the weight of the log, we can write:

0.6 * m * g = 1000 * V * g

Here, g represents the acceleration due to gravity, which is approximately 9.8 m/s^2.

Simplifying the equation, we find:

0.6 * m = 1000 * V

Now, we can solve for the density of the wood, which is given by:

Density of wood = Mass of log / Volume of log = m / V

Substituting the value of m from the previous equation, we get:

Density of wood = (0.6 * 1000 * V) / V = 600 kg/m^3

Therefore, the density of the wood is 600 kg/m^3.

Please note that this calculation assumes that the log is made of a single type of wood with a uniform density throughout. In reality, the density of wood can vary depending on the species and other factors.