# Fluid mechanics,wooden block in water and oil

• hannam
In summary, a cubical block of wood with dimensions of 10 cm on each side is placed in a glass cup with an open end. The block is in equilibrium at the interface between water and oil, with the lower surface of the wood 2 cm below the interface. The density of the oil is 790 kg/m3. The questions ask for the absolute pressure at the lower and upper face of the wood block and the mass and density of the block. Using the equations fb=p liquid * v sinked*g, p object * v object = p liquid * v sinked, and P1= Po+ p*h*g, a solution can be attempted. However, without clarification on the edge length of the wood, finding the
hannam

## Homework Statement

A cubical block of wood, 10 cm on a side, is placed in a
glass cup whose higher end is open to the atmosphere. The
wood is in equilibrium at the interface between water and oil
with wood’s lower surface 2 cm below the interface. The
density of oil is 790 kg/m3.
a) What is the (absolute) pressure at the lower and upper face of
the wood block?
b) What are the mass and density of the block?

## Homework Equations

fb=p liquid * v sinked*g
p object * v object = p liquid * v sinked
P1= Po+ p*h*g

## The Attempt at a Solution

0.02*1 + 790*x = p wood*(2+x) =m
does it say edge of the wood is 10 cm? my english is not very good and if it is 10 cm, i can find m.
but still i have no idea about the pressure part.
my exam is tomorrow. any help is appreciated :(

here s the pic of question

#### Attachments

• fluidmech.png
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## 1. How does the density of the wooden block affect its buoyancy in water and oil?

The density of the wooden block plays a significant role in its buoyancy in both water and oil. Buoyancy is determined by the difference in density between the object and the surrounding fluid. If the density of the wooden block is greater than that of the fluid, it will sink. However, if the density of the wooden block is less than that of the fluid, it will float. Since oil is denser than water, the wooden block will float higher in oil compared to water.

## 2. How does the shape of the wooden block affect its buoyancy in water and oil?

The shape of the wooden block also affects its buoyancy in water and oil. Objects with a larger surface area will have more buoyancy compared to objects with a smaller surface area. This is because the larger surface area allows for more contact with the surrounding fluid, resulting in more upward force. Therefore, a block with a larger surface area will float higher in water and oil compared to a block with a smaller surface area.

## 3. Why does the wooden block float in both water and oil?

The wooden block floats in both water and oil because it is less dense than both fluids. This means that the upward force of buoyancy is greater than the downward force of gravity, allowing the block to float. Additionally, the surface tension of water and oil also helps to keep the block afloat by creating a barrier between the block and the surrounding fluid.

## 4. How does the viscosity of the fluid affect the movement of the wooden block?

The viscosity of a fluid, or its resistance to flow, can affect the movement of the wooden block. In a more viscous fluid like oil, the wooden block will experience more resistance as it moves through the fluid. This can result in slower movement or even cause the block to remain stationary. In a less viscous fluid like water, the block will experience less resistance, allowing it to move more easily.

## 5. Can the wooden block float at different levels in water and oil?

Yes, the wooden block can float at different levels in water and oil. This is because the buoyant force is dependent on the difference in density between the object and the surrounding fluid. Since water and oil have different densities, the wooden block will float at different levels in each fluid. Additionally, the position of the block can also be affected by factors such as the shape and size of the block, as well as the surface tension of the fluids.

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