Surface tension, property of a liquid surface displayed by its acting as if it were a stretched elastic membrane. This phenomenon can be observed in the nearly spherical shape of small drops of liquids and of soap bubbles. Because of this property, certain insects can stand on the surface of water. A razor blade also can be supported by the surface tension of water. The razor blade is not floating: if pushed through the surface, it sinks through the water.
Surface tension depends mainly upon the forces of attraction between the particles within the given liquid and also upon the gas, solid, or liquid in contact with it. The Molecules in a drop of water, for example, attract each other weakly. Water molecules well inside the drop may be thought of as being attracted equally in all directions by the surrounding molecules. However, if surface molecules could be displaced slightly outward from the surface, they would be attracted back by the nearby molecules. The energy responsible for the phenomenon of surface tension may be thought of as approximately equivalent to the work or energy required to remove the surface layer of molecules in a unit area. Surface tension may be expressed, therefore, in units of energy (joules) per unit area (square metres). Water has a surface tension of 0.07275 joule per square metre at 20 °C (68 °F). In comparison, organic liquids, such as benzene and alcohols, have lower surface tensions, whereas mercury has a higher surface tension. An increase in temperature lowers the net force of attraction among molecules and hence decreases surface tension.
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Surface tension is the tendency of a liquid surface to contract into the smallest possible area. This is caused by the cohesive forces between the liquid molecules. Cohesion is the force that holds molecules of the same substance together. The cohesive forces between water molecules are very strong, which is why water has a high surface tension.
Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to external forces like gravity. The surface tension of a liquid is responsible for capillary action. When a liquid is in contact with a solid surface, the liquid molecules at the surface are attracted to the solid molecules. This attraction causes the liquid molecules to pull together, creating a surface tension. The surface tension of the liquid is what allows it to rise up a narrow tube, even against the force of gravity.
Contact angle is the angle formed between a liquid and a solid surface at the point of contact. The contact angle is affected by the surface tension of the liquid, the wettability of the solid surface, and the relative adhesion between the liquid and the solid.
Dew point is the temperature at which the air is saturated with water vapor. At this temperature, the water vapor in the air condenses into liquid water. The dew point is affected by the humidity of the air and the temperature of the air.
A droplet is a small amount of liquid that is free to move. Droplets are formed when a liquid is poured or when it is squeezed out of a container. The shape of a droplet is determined by the surface tension of the liquid.
A meniscus is the curved surface of a liquid that is in contact with a solid surface. The meniscus is caused by the surface tension of the liquid. The shape of the meniscus is affected by the wettability of the solid surface.
Surface energy is the energy required to increase the surface area of a liquid. The surface energy of a liquid is affected by the surface tension of the liquid. The surface energy of a liquid is also affected by the temperature of the liquid.
The surface tension of water is very high. This is because water molecules are polar. The positive end of a water molecule is attracted to the negative end of another water molecule. This attraction creates a strong cohesive force between water molecules. The high surface tension of water allows it to form droplets, climb up narrow tubes, and break through the surface of a liquid.
A tensiometer is a device that measures the surface tension of a liquid. There are many different types of tensiometers, but they all work by measuring the force required to break the surface of a liquid.
Van der Waals forces are weak attractive forces that exist between all molecules. These forces are caused by the temporary dipoles that are created when the electrons in a molecule move around. Van der Waals forces are responsible for the cohesion of liquids and the adhesion of liquids to solids.
Surface tension is a very important property of liquids. It affects many of the properties of liquids, such as their ability to form droplets, climb up narrow tubes, and break through the surface of a liquid. Surface tension is also responsible for many of the phenomena that we see in nature, such as the formation of dew and the wetting of surfaces.
Topic: Friction
What is friction?
Friction is a force that opposes the relative motion of two objects or materials.
What are the different types of friction?
There are two main types of friction: static friction and kinetic friction. Static friction is the force that opposes the start of motion between two objects. Kinetic friction is the force that opposes the motion of two objects that are already in contact.
What are the causes of friction?
Friction is caused by the interaction of the microscopic surface features of two objects. When two objects come into contact, the microscopic bumps and grooves on their surfaces interlock, creating a force that resists the relative motion of the objects.
What are the effects of friction?
Friction can have both positive and negative effects. On the one hand, friction can be useful for providing traction and preventing objects from slipping. On the other hand, friction can also be a source of wear and tear on objects, and it can make it difficult to move objects over long distances.
How can friction be reduced?
Friction can be reduced by using lubricants, which reduce the interaction between the microscopic surface features of two objects. Friction can also be reduced by using smooth surfaces, which have fewer microscopic bumps and grooves.
Topic: Gravity
What is gravity?
Gravity is a force that attracts any two objects with mass. The more mass an object has, the stronger its gravitational pull.
What are the effects of gravity?
Gravity causes objects to fall to the ground. It also keeps the Earth in orbit around the Sun and the Moon in orbit around the Earth.
What is the law of universal Gravitation?
The law of universal gravitation states that every object in the universe attracts every other object with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
What is the escape velocity?
The escape velocity is the minimum speed an object must have to escape the gravitational pull of a planet or other celestial body.
What is black hole?
A black hole is a region of space where gravity is so strong that nothing, not even Light, can escape.
Topic: Electromagnetism
What is electromagnetism?
Electromagnetism is the force that causes electric and magnetic fields to interact with each other.
What are the different types of electromagnetism?
There are two main types of electromagnetism: static electricity and electromagnetism. Static electricity is the build-up of electric charge on an object. Electromagnetism is the production of a Magnetic Field by an electric current.
What are the causes of electromagnetism?
Electromagnetism is caused by the movement of electrons. When electrons move, they create an electric field. When an electric field changes, it creates a magnetic field.
What are the effects of electromagnetism?
Electromagnetism has many effects, including electricity, Magnetism, and light. Electricity is the flow of electrons through a conductor. Magnetism is the force that attracts or repels objects. Light is a form of electromagnetic radiation.
How can electromagnetism be used?
Electromagnetism can be used to generate electricity, create magnetic fields, and produce light. It is also used in many other applications, such as radio, television, and computers.
What is a wave?
A wave is a disturbance that travels through a medium, such as water, air, or solid.
What are the different types of waves?
There are many different types of waves, including mechanical waves, Electromagnetic Waves, and Sound waves. Mechanical waves are waves that require a medium to travel through, such as water waves or sound waves. Electromagnetic waves are waves that can travel through the vacuum of space, such as light waves or radio waves. Sound waves are waves that travel through air or other fluids.
What are the causes of waves?
Waves can be caused by many things, such as wind, Earthquakes, or explosions.
What are the effects of waves?
Waves can have many effects, such as causing erosion, creating tides, and generating electricity.
How can waves be used?
Waves can be used for many things, such as Communication, transportation, and energy production.
The force that acts at the surface of a liquid and tries to minimize the surface area is called:
(A) Surface tension
(B) Viscosity
(C) Adhesion
(D) Cohesion
Which of the following is not an example of surface tension?
(A) A water strider can walk on water.
(B) A drop of water forms a spherical shape.
(C) A water balloon will break if it is thrown against a hard surface.
(D) A water molecule is attracted to other water molecules.
Which of the following is the most important factor that affects surface tension?
(A) The temperature of the liquid
(B) The type of liquid
(C) The surface area of the liquid
(D) The presence of impurities in the liquid
Which of the following is an example of how surface tension can be used to our advantage?
(A) We can use surface tension to create soap bubbles.
(B) We can use surface tension to make paperclips float on water.
(C) We can use surface tension to make water droplets bead up on a waxed surface.
(D) All of the above.
Which of the following is an example of how surface tension can be harmful?
(A) When you spill water on a table, the water will spread out and make a mess.
(B) When you wash your hands, the soap will break the surface tension of the water and make it easier to rinse off the dirt.
(C) When you cook pasta, the water will boil and the pasta will float to the surface.
(D) All of the above.
Which of the following is not a property of water?
(A) Water is a liquid.
(B) Water is a polar molecule.
(C) Water has a high surface tension.
(D) Water is a good conductor of electricity.
Which of the following is not an example of how water is important for life?
(A) Water is used for drinking and cooking.
(B) Water is used for Irrigation.
(C) Water is used for transportation.
(D) Water is used to generate electricity.
Which of the following is not an example of how water can be harmful to life?
(A) Water can cause flooding.
(B) Water can cause erosion.
(C) Water can cause disease.
(D) Water can be used to extinguish fires.
Which of the following is the most important reason why water is important for life?
(A) Water is a necessary component of all living things.
(B) Water is a good solvent.
(C) Water has a high surface tension.
(D) Water is a good conductor of electricity.
Which of the following is not a way to conserve water?
(A) Take shorter showers.
(B) Turn off the faucet when you brush your teeth.
(C) Fix any leaks in your home.
(D) Water your lawn every day.