Question

Буратино массой 40 кг сделан из дерева, его плотность 0,8 г/см3. Утонет ли Буратино в воде, если к его ногам привязать кусок стального рельса массы 20 кг? Считать, что плотность стали в 10 раз больше плотности воды.

Answer 1

p(плотность)=m(масса)/v(объём)
ОБъём постоянен (по условию получается)
v=m/p=40/0.8=50

p=(40+20)/50=1.2.(из формулы выше)
Да,утонет,т.к 1.2>1 (это плотность воды).

Answer 2

Question: Will Buratino drown in water if a piece of steel rail weighing 20 kg is tied to his feet? Buratino weighs 40 kg and is made of wood, with a density of 0.8 g/cm3. Assume that the density of steel is 10 times greater than the density of water.

To determine if Buratino will drown in water with a piece of steel rail tied to his feet, we need to compare the buoyant force acting on Buratino with the gravitational force pulling him down.

Buoyant Force:

The buoyant force is the upward force exerted on an object submerged in a fluid. It is equal to the weight of the fluid displaced by the object. In this case, the fluid is water.

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

Buoyant force = Weight of water displaced

The weight of water displaced is equal to the volume of water displaced multiplied by the density of water and the acceleration due to gravity.

Gravitational Force:

The gravitational force pulling Buratino down is equal to his weight, which can be calculated using the formula:

Gravitational force = Mass of Buratino * Acceleration due to gravity

The acceleration due to gravity is approximately 9.8 m/s2.

Comparison:

If the buoyant force is greater than or equal to the gravitational force, Buratino will float in water. If the gravitational force is greater, Buratino will sink.

To determine the volume of water displaced by Buratino, we can use the formula:

Volume = Mass / Density

Let's calculate the buoyant force and gravitational force to determine if Buratino will drown in water.

Calculation:

1. Calculate the volume of water displaced by Buratino: - Mass of Buratino = 40 kg - Density of Buratino = 0.8 g/cm3 = 0.8 kg/dm3 = 800 kg/m3 - Volume of water displaced = Mass of Buratino / Density of water - Volume of water displaced = 40 kg / 800 kg/m3 = 0.05 m3

2. Calculate the buoyant force: - Buoyant force = Weight of water displaced - Buoyant force = Volume of water displaced * Density of water * Acceleration due to gravity - Buoyant force = 0.05 m3 * 1000 kg/m3 * 9.8 m/s2 = 49 N

3. Calculate the gravitational force: - Gravitational force = Mass of Buratino * Acceleration due to gravity - Gravitational force = 40 kg * 9.8 m/s2 = 392 N

Conclusion:

Based on the calculations, the buoyant force acting on Buratino is 49 N, while the gravitational force pulling him down is 392 N. Since the gravitational force is greater than the buoyant force, Buratino will sink in water even if a piece of steel rail weighing 20 kg is tied to his feet.

Please note that the calculations assume ideal conditions and do not take into account other factors such as the shape and size of Buratino or the effects of air trapped in the wood.