Engineering: Convection

Which statements accurately describe convection in water? Check all that apply. Cold water sinks because it is less dense than warm water. Cold water sinks because it is more dense than warm water. Cold water rises because it is more dense than warm water. Warm water sinks because it is less dense than cold water. Warm water rises because it is less dense than cold water. Warm water rises because it is more dense than cold water.

Complete the statements about convection currents. Convection currents occur in fluids because of temperature and ________differences. Convection currents transfer_________energy throughout a fluid. They continue until all of the fluid is at the same temperature.

In which layer of Earth's interior does convection occur? crust mantle outer core inner core

How is thermal energy transferred during convection? by physical contact by electromagnetic waves by movement in fluids by mechanical waves

Use the drop-down menus to complete the sentences describing what happens when the temperature of a fluid increases. The kinetic energy of the molecules: The speed of the molecules: The density of the fluid: The fluid:

Which statements best describe convection? Check all that apply. Convection occurs in solids. Convection occurs in liquids and gases. Convection transfers thermal energy. Convection transfers potential energy. Convection occurs until all of the fluid is at the same temperature. Convection occurs only one time, no matter the temperature.

Which describes the motion in a convection current? horizontal motion only vertical motion only linear motion circular motion

Refer to the image of a lava lamp to answer the question. In a lava lamp, a waxy substance rises and falls repeatedly. What causes the waxy substance to rise? Check all that apply. The waxy substance is cold. The waxy substance is warm. The waxy substance is less dense than the surrounding liquid. The waxy substance is more dense than the surrounding liquid. Convection is occurring.

What happens at night? Cool air over the ocean moves onshore. Cool air over the land moves offshore. Warm air over the ocean moves onshore. Warm air over the land moves offshore.

Use the drop-down menus to identify each labeled part of the diagram. Label A: Label B: Label C:

How is thermal energy transferred during convection? by physical contact by electromagnetic waves by movement in fluids by mechanical waves

Use the drop-down menus to complete the sentences describing what happens when the temperature of a fluid increases. The kinetic energy of the molecules: The speed of the molecules: The density of the fluid: The fluid:

Which statements best describe convection? Check all that apply. Convection occurs in solids. Convection occurs in liquids and gases. Convection transfers thermal energy. Convection transfers potential energy. Convection occurs until all of the fluid is at the same temperature. Convection occurs only one time, no matter the temperature.

Which describes the motion in a convection current? horizontal motion only vertical motion only linear motion circular motion

Refer to the image of a lava lamp to answer the question. In a lava lamp, a waxy substance rises and falls repeatedly. What causes the waxy substance to rise? Check all that apply. The waxy substance is cold. The waxy substance is warm. The waxy substance is less dense than the surrounding liquid. The waxy substance is more dense than the surrounding liquid. Convection is occurring.

Use the diagram to answer the question. What happens at night? Cool air over the ocean moves onshore. Cool air over the land moves offshore. Warm air over the ocean moves onshore. Warm air over the land moves offshore.

Use the drop-down menus to identify each labeled part of the diagram. Label A: Label B: Label C:

Which best describes convection? It relies on the collision of particles within or between substances. It occurs in solids, liquids, or gases that are heated. It results when portions of a liquid cool and rise. It is driven by temperature differences within a fluid.

Water is boiling in a clear pot, as shown in the picture. Which takes place as water cycles from the bottom of the pot toward the top? Thermal energy is transferred. Water molecules gain kinetic energy. Chemical energy is transferred. Water molecules gain thermal energy.

A student places a large pot of cold water on a stove and heats it for one minute. Then she takes the pot of water off the burner and places it on the counter. Which best describes the convection currents? Convection currents move thermal energy from the stove to the pot, and then from the pot to the water. After the stove is turned off, convection currents continue to transfer energy through the water for a period of time. Convection currents in the water cause warmer, denser water to rise and transfer energy upward. When the stove is turned on, convection currents cause an increase in the chemical energy of water molecules.

The diagram shows how air circulation forms a sea breeze on a warm day. Which best describes what is happening in the diagram? At point 1, the air in the convection current is warmer and denser than at point 3 because its molecules contain more kinetic energy. At point 2, the air absorbs thermal energy from the surrounding air, which causes it to become heavier and sink. At point 3, the air in the convection current is cooler and lighter than the air in other parts of the current, so it is preparing to rise. At point 4, thermal energy from warm air over the land is transferred upward toward cooler areas of the atmosphere.

The diagram shows the motion of a group of water molecules over a heat source. How do the molecules at point A compare to the molecules at point B? Check all that apply. They are closer together. They are farther apart. They are moving faster. They are moving slower. They have gained energy. They have lost energy.

Which best describes the convection currents in Earth's mantle? They transfer potential energy away from Earth's core toward its crust. They transfer thermal energy away from Earth's core toward its crust. They transfer chemical and thermal energy in a circular pattern. They transfer chemical and potential energy in a circular pattern.

Which best describes the shape of a convection current? linear spiral circular wave

The lava lamp has a light bulb as a heat source at its base. The lamp contains a colored, waxy fluid that can be observed moving in clumps through a clear liquid. As the clump of colored fluid at the bottom of the lava lamp rises to the top, which will increase? its density its temperature the kinetic energy of its molecules the space between its molecules

The lava lamp has a light bulb as a heat source at its base. The lamp contains a colored, waxy fluid that can be observed moving in clumps through a clear liquid. Which indicates that the clump of waxy fluid at the center of the lamp is moving downward rather than upward? It is less dense than the surrounding liquid. Its molecules are losing kinetic energy. Its molecules begin to slow down before they become faster. Its temperature increases before it decreases again.

Water is boiling in a clear pot, as shown in the picture. How do the water molecules closest to the burner compare to the water molecules closest to the surface of the liquid? They are more spread out and moving faster than those at the surface. They are closer together and moving faster than those at the surface. They are more spread out and moving slower than those at the surface. They are closer together and moving slower than those at the surface.

The diagram shows the sun's interior. Convection currents are present in the convection zone. Which best describes how fluids change as they travel through different portions of the convection currents? They change to solids at the outer portion of the convection currents. They change to solids at the inner portion of the convection currents. They become more dense at the outer portion of the convection currents. They become more dense at the inner portion of the convection currents.

A student heats a liquid on a burner. What happens to the portion of liquid that first begins to warm? Check all that apply. It becomes more dense. It becomes less dense. It releases energy to the environment. It absorbs energy from the environment. It rises upward. It sinks downward.

In a convection current, as the temperature of a fluid increases, its decreases.

The diagram shows currents that form as water is heated. Which would most likely contain this same type of current? the air above a wildfire a carton of milk in a refrigerator a snowdrift on a shady mountainside a boulder in a hot desert

Which is required for convection to occur? a solid substance a heat source boiling water air molecules

When Xavier places his hands near a light bulb, he notices that certain areas around the light bulb are warmer than others. Which best explains this? The areas to the sides of the light bulb are warmest because of conduction. The areas to the sides of the light bulb are warmest because of convection. The area directly above the light bulb is warmest because of conduction. The area directly above the light bulb is warmest because of convection.

Which area of Earth is most similar to the sun's convection zone? the crust the equator the mantle the poles

Yami pours powdered cocoa mix into milk and stirs it. Then she microwaves the mixture for three minutes. When she takes the cup out, the handle is very warm. Steam rises from the cup, so she blows it before taking a sip. In which part of this scenario can convection be best observed? stirring powdered cocoa mix into milk touching the warm handle of the cup rising steam from the cup of cocoa blowing on the hot cocoa to cool it

Where could convection currents form? Check all that apply. in a sand dune in a freshwater lake in the atmosphere in outer space in Earth's mantle

Convection only occurs in .

How does an increase in thermal energy affect molecules? They stop moving. They begin to vibrate more. They decrease in temperature. They lose kinetic energy.

Which contains the particles that are vibrating fastest? boiling water frozen water room-temperature water cold tap water

Conduction involves the transfer of electric charge or .

Alana drew diagrams to show how particles in a spoon move before and after the spoon is placed in hot liquid. Which best explains how to correct Alana's error? Make the particles in both diagrams larger. Show more movement in the "Before" diagram. Add more particles to the "After" diagram. Switch the labels on the diagrams.

Which describes how fast-moving particles assist in transferring thermal energy to a cup after hot tea is poured into it? They replace slow-moving particles. They collide with slow-moving particles. They collide with other fast-moving particles. They are replaced by slow-moving particles.

When Object 1 came into contact with Object 2, Object 2 got warmer. What can be concluded about the objects before they came into contact with each other? Object 2 did not have thermal energy. Object 1 had faster-moving particles. Object 1 had less thermal energy. Object 2 had fewer particles.

Most thermal conductors are .

Which materials are typically used as thermal insulators? Check all that apply. copper foam ceramic wood plastic

Which best explains why metal cooking utensils often have plastic coating on their handles? Plastic melts less easily and lasts longer than metal. Plastic reduces the transfer of thermal energy to hands holding the utensils. Plastic molds more easily into shapes like long, thin handles. Plastic increases the rate of conduction from the utensil to the food.

A scientist designed a foam container to help keep frozen foods from melting. Which bestexplains how the foam works? It removes thermal energy from the air inside the container. It removes thermal energy from the frozen foods inside the container. It reduces the amount of thermal energy that is transferred from inside to outside the container. It reduces the amount of thermal energy that is transferred from outside to inside the container.

How does a foam-filled winter coat help keep a person warm? It slows down the transfer of thermal energy from outside to inside the coat. It slows down the transfer of thermal energy from inside to outside the coat. It speeds up the transfer of thermal energy from outside to inside the coat. It speeds up the transfer of thermal energy from inside to outside the coat.

Keesha conducts an experiment by pouring equal amounts of boiling water into four containers. The containers are the same size and shape, but they are made of different materials. The chart lists the containers according to their materials. Using protective gloves, Keesha carefully touches each container immediately after pouring the water. Which container was likely the hottest? W X Y Z

How do the metal aluminum coils in an air conditioner help keep a house cool? They insulate the house from outside thermal energy. They conduct thermal energy from inside the house and release it outside the house. They insulate the surrounding air from indoor thermal energy. They conduct thermal energy from outside the house and release it inside the house.

What must be true about two objects for conduction to take place? The objects must be different temperatures and they must be in contact. The objects must be the same temperature and they must be in contact. The objects must be different temperatures and they must be insulators. The objects must be the same temperature and they must be insulators.

The diagram shows movement of thermal energy. In which areas of the diagram does conduction occur? W and X X and Z Y and Z Z and W

Earl is using his hands to hold a metal pan 10 centimeters above a hot burner. How can this scenario be changed to demonstrate conduction between the pan and the burner? increase the temperature of the burner use a glass pan instead of a metal pan use foam potholders to hold the pan touch the pan to the burner

Conduction can occur within a single substance, but parts of the substance must have which property? different temperatures different textures different particle sizes different colors

What occurs when someone places an ice pack on an injured ankle? Conduction causes the ice pack to lose thermal energy. Conduction causes the ankle to gain thermal energy. Cold from the ice pack is transferred to the ankle. Heat from the ankle is transferred to the ice pack.

Which explains why conduction is unlikely when ice is placed on a freezer shelf? There is no direct contact. The ice is too cold. The shelf acts as an insulator. The ice and shelf are the same temperature.

________ is the thermal energy that flows from one substance to another when the substances differ in temperature.

Heat is most closely related to energy.

Ixchelt burns her tongue when she takes a sip of hot coffee from her mug. Which part of this example represents heat? the thermal energy moving from the coffee to her tongue the thermal energy moving from her tongue to the coffee her coffee her tongue

Which best explains why water boils in a pot sitting over fire? Heat energy is created from the thermal energy in the air. Heat energy is transferred from the water to the fire. Thermal energy from the fire moves to the water in the form of heat. Thermal energy from the surrounding air moves to the water.

Isaac wants to make s'mores. He holds a marshmallow on a metal skewer over a fire. A few seconds later, the marshmallow is cooked and the skewer feels warm. What most likelyhappened? The fire heated the surrounding air, which cooked the marshmallow. The heat generated from the marshmallow flowed in the form of thermal energy to the skewer and fire. The heat from the skewer cooked the marshmallow. Thermal energy in the form of heat moved from the fire to the skewer and marshmallow.

A burner on a stove produces temperature. thermal energy. hotness. fire energy.

Nuclear reactions in a reactor produce a lot of thermal energy. That energy then flows and warms up water, which boils and produces steam. The steam then turns turbines that generate electricity. Which statement below can be made about the production of electricity in a nuclear reactor? Heat flows in the form of electricity. Heat flows from the reactor to the water. The water produces heat. The steam produces heat.

Shelly tells a friend that her computer needs to be fixed because it has been producing a lot of heat and is smoking. Where is the error in her statement? Heat cannot be described as having been produced. Thermal energy cannot be produced by electronics. Her computer should be producing a lot of heat and does not need to be fixed. Her computer is producing thermal energy, not heat.

Heat flows from substances.

Which best describes the direction of heat? from a substance with no thermal energy to a substance with high amounts of thermal energy from a substance with less thermal energy to a substance with more thermal energy from a cooler substance to a warmer substance from a warmer substance to a cooler substance

If a cup of coffee is at 90°C and a person with a body temperature of 36°C touches it, how will heat flow between them? from the hand to the cup from the cup to the hand from the cup to the surrounding air from the hand to surrounding air

A stovetop burner on medium reaches 200°C. Which other objects will heat from the burner flow to? Check all that apply. the surrounding air a cool pan a pan heated to 223°C cool water inside a pan someone who touches it

Which substance has the most thermal energy and will have the most heat flow from it? a stovetop burner on medium (200°C) a nuclear reactor core (1000°C) the human body (36°C) air at room temperature (32°C)

The metal aluminum coils in an air conditioner conduct thermal energy from inside the house and release it outside the house. What can be said about the coils when they are accepting the heat inside the house? They must be warmer than the air inside the house. They must be cooler than the air inside the house. They must have more thermal energy than the air inside the house. They must be more insulated than the air inside the house.

What must be true about two objects if heat is flowing between them? The objects must be different temperatures. The objects must be the same temperature. The objects must both be over room temperature. The objects must both be under room temperature.

This chart lists four examples of two objects that are in contact. Which statement accurately describes the flow of heat in each example? Heat will flow from Object 1 to Object 2 in examples 2 and 4, and heat will flow from Object 2 to Object 1 in examples 1 and 3. Heat will flow from Object 1 to Object 2 in examples 1 and 3, and heat will flow from Object 2 to Object 1 in examples 2 and 4. Heat will flow from Object 1 to Object 2 in Example 3, and heat will flow from Object 2 to Object 1 in examples 1, 2, and 4. Heat will flow from Object 1 to Object 2 in examples 1, 2, and 4, and heat will flow from Object 2 to Object 1 in Example 3.

____________ heat is the amount of heat required to change the temperature of 1 gram of a substance by 1°C, and it is related to the chemical composition of the substance.

Which factors affect heat transfer between a warm and a cool substance? the time it took to heat the substance, the area of contact, and the specific heats of the substances the amount of time of contact, the area of contact, and the specific heats of the substances the time it took to heat the substance, the area of the substances, and the specific heats of the substances the amount of time of contact, the area of the substances, and the specific heats of the substances

Heat transfer between two substances is affected by specific heat and the chemical composition of the substances. state of matter of the substances at room temperature. thermal equilibrium of the substances. amount of time and area of physical contact between the substances.

Which substance is most likely to heat up the fastest? water (specific heat of 4.19 /g • C°) copper (specific heat of .39 /g • C°) aluminum (specific heat of .90 /g • C°) dry air (specific heat of 1.01 /g • C°)

Mintu wants to increase the heat transfer between a metal iron and another piece of metal he wants to shape. He decides to increase the time the two metals are in contact, use a larger metal iron, and use a new metal material with a higher specific heat. Where is Mintu's error? Mintu should have decreased the size of the metal iron. Mintu should have decreased the time he touches the two metals. Mintu should have chosen a material with a lower specific heat. Mintu should have chosen a material the same temperature as the iron.