Fluid friction is friction that occurs when things move through a fluid. A fluid is a material that can flow and form itself according to its container. Liquids and gases are examples of fluids.
Fluids (air or liquid) exert a resisting force on objects moving through them. This resisting force is called fluid friction. For instance, air resistance on an aeroplane or water resistance on a boat is fluid friction.
Table of Contents
Other Name of Fluid Friction
Drag is another name for fluid friction. It is generally used in the studies of the speed of an object across a fluid. Drag force is directly proportional to velocity and acts in the opposite direction to motion.
The factors affecting fluid friction are:
What is Fluid Friction?
Fluid friction occurs when fluid layers move relative to one another. The term for this internal resistance to flow is viscosity. The viscosity of a fluid is commonly referred to as its “thickness. Since all-natural fluids resist shearing, they are vicious. It is useful to consider an inviscid fluid or an ideal fluid that has no resistance to shearing and so is not viscous. A common example of fluid friction is When you stick your hand out a car window, and the air pushes on it.
Some other examples of fluid friction are listed below:
- The movement of your coffee as you stir it with a spoon (external).
- Submarine moving through water (external).
- When a speed boat moves in water its speed is reduced due to fluid resistance.
Ways to reduce Fluid Friction
Objects that move in fluids, such as boats, aircraft, and vehicles, have their bodies streamlined to decrease friction between the objects’ bodies and the fluid.
Polishing the surface smoothens the surface and reduces friction.
Types of Friction
- Dry friction: The resistance to relative lateral motion between two solid surfaces in contact.
- Fluid friction: The friction that occurs between moving layers of a viscous fluid.
- Lubricated friction: Fluid friction in which two solid surfaces are separated by a lubricating fluid.
- Skin friction: The force that resists fluid motion across the surface of a body.
- Internal friction: The force that resists motion between the components that make up a solid substance when it deforms.
Daily Life Significance of Fluid Friction
Fluid friction, also known as viscous or drag force, plays a significant role in our daily lives. It is a force that opposes the motion of an object through a fluid (gas or liquid) and arises from the interaction between the fluid and the surface of the object.
Here are some examples of the significance of fluid friction in daily life:
- Driving a car: When you drive a car, you experience the effect of fluid friction in the form of air resistance or drag force. The air molecules exert a force on the car as it moves through the air, which opposes the car’s motion and increases fuel consumption.
- Swimming: When you swim, the water provides resistance to your movement, making it harder to swim faster. The force of the water against your body is an example of fluid friction.
- Design of buildings: Fluid friction is an important consideration in the design of buildings and other structures. Wind, which is a fluid, exerts a force on the building that can cause it to sway or vibrate. Engineers must account for this force in the design process to ensure the building can withstand wind loads.
- Aerospace engineering: Fluid friction is a critical factor in aerospace engineering. When designing planes and rockets, engineers must consider the drag force that the vehicle will experience as it moves through the air or space. Reducing drag is essential to achieving maximum efficiency and speed.
- Cooking: Fluid friction plays a role in cooking, especially when working with liquids. When stirring a liquid, the viscosity of the liquid affects the force needed to move the spoon through it. The resistance to motion is an example of fluid friction.
Fluid Friction Formula
The formula for fluid friction or drag force is given:
Fd = 1/2 * rho * v^2 * Cd * A
where:
- Fd is the drag force
- rho is the density of the fluid
- v is the velocity of the object relative to the fluid
- Cd is the drag coefficient, which depends on the shape of the object
- A is the cross-sectional area of the object perpendicular to the direction of motion.
The drag coefficient Cd represents the amount of resistance that the object experiences due to its shape and can be determined experimentally. The larger the drag coefficient, the more resistance the object experiences from the fluid, and the larger the drag force.
Note that the formula above assumes that the fluid is moving parallel to the object’s surface, and the object is moving at a constant velocity. The formula can be more complex in other situations, such as when the fluid is turbulent or the object is accelerating.
Dynamic Viscosity
The resistance to the flow of one layer of fluid across another layer of fluid is defined as dynamic viscosity.
Viscosity is caused by friction inside a fluid. The intermolecular forces that exist between particles in a fluid (air or liquid) cause it.
Summary
- Friction is the force that resists motion between any two surfaces that come into touch with one another. Friction may be classified into four types: static, sliding, rolling, and fluid friction.
- Fluid friction is friction that occurs when things move through a fluid.
- Fluid friction occurs in fluids, which are liquids or gases.
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Frequently Asked Questions
1. What is friction in simple words?
Friction is the force that exists between two surfaces that are sliding or trying to glide across one other. When you try to push a book across the floor, for example, friction makes it harder. Friction always acts in the opposite direction that the item is moving or attempting to move.
2. Laminar flow definition?
Laminar flow is a form of fluid (gas or liquid) flow in which the fluid flows smoothly and in predictable patterns. In contrast, turbulent flow is a type of fluid in which the fluid fluctuates and mixes irregularly.
3. What is the SI unit of viscosity?
The unit of viscosity is newton-second per square meter, which is usually expressed as pascal-second in SI units.
3. What is the ideal gas law?
Ideal gas law states that the pressure of gas times its volume equals the number of moles of the gas times a constant (R) times the temperature of the gas.
4. What temp does gas freeze?
Water’s normal freezing temperature is zero degrees Celsius or 32 degrees Fahrenheit.
5. Is air a homogeneous mixture?
Air is a homogenous mixture of many gases. The atmosphere is made up of nitrogen, oxygen (essential for animal and human life), carbon dioxide, water vapour, and trace amounts of other elements (argon, neon, etc.).
6. Air pressure definition?
Air pressure is the pressure exerted on objects from the air or the Earth’s atmosphere.
The average value for the atmospheric pressure at sea level is defined as 1 atmosphere (atm).
7. What is the specific heat of air?
The specific heat of air at constant pressure is 1.005 kJ/kg K and the specific heat of air at constant volume is 0.718 kJ/kg K.
8. What is an ideal gas?
An ideal gas is a hypothetical gas whose molecules take up little space and have no interactions and hence obey the gas laws precisely.
9. Otto cycle?
The Otto Cycle shows how heat engines produce motion from fuel. Like other thermodynamic cycles, this one turns chemical energy into thermal energy and then into motion (work).
10. What is a PV diagram?
The pressure-volume diagram (abbreviated as the PV diagram) is a graphical representation of pressure fluctuations in a closed system. P-V diagrams may be used to calculate the efficiency of a system as well as the work done by or on the system.
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