Heat Transfer and Convection Currents

Heat transfer in a fluid takes place by ________________ when there is a temperature difference.

• Conduction

• Convection

• Radiation

• Insulation

Answer explanation

Heat transfer in a fluid occurs through convection when there is a temperature difference. Convection involves the movement of the fluid itself, transferring heat energy.

How is heat transferred from the sun to the earth?

• by convection, as warm air sinks

• by cooler air rising from the earth

• by electromagnetic waves (radiation)

• by direct transfer of energy from the sun to the earth

Answer explanation

Heat is transferred from the sun to the earth by direct transfer of energy, not by convection, cooler air rising, or electromagnetic waves.

Tags

NGSS.MS-PS4-2

What type of heat transfer is taking place when you feel the warmth of a fire from a distance?

• conduction

• radiation

• convection

Answer explanation

The warmth of a fire from a distance is due to radiation, which is the transfer of heat through electromagnetic waves.

Why does an ice cube make your hand feel cold?

• The ice cube makes your hand feel cold because it releases cold energy.

• The ice cube makes your hand feel cold because it contains a cooling agent.

• The ice cube makes your hand feel cold because it absorbs heat from your hand.

• The ice cube makes your hand feel cold because it creates a vacuum around your hand.

Answer explanation

An ice cube makes your hand feel cold because it absorbs heat from your hand.

Tags

NGSS.MS-PS1-4

When the temperature increases, the density of the liquid water ____________.

• Increases

• Decreases

• Stays the same

Answer explanation

When the temperature increases, the viscosity of liquid water decreases.

What happens to the volume of water as it warms up?

• The volume of water decreases as it warms up.

• The volume of water increases as it warms up.

• The volume of water remains the same as it warms up.

• The volume of water first increases, then decreases as it warms up.

Answer explanation

As water warms up, its volume increases. This is because the molecules move faster and spread out, occupying more space.

Tags

NGSS.MS-PS1-4

Can conduction occur in a vacuum?

• No, it requires a medium.

• Yes, it can occur in any state.

• Yes, only in vacuum.

• No, only in solid, liquid, and gas.

Answer explanation

Conduction can occur in a gas, as well as in solid and liquid. The correct choice is 'Yes, in a solid, liquid, and gas.'

What is the term used to describe the measure of mass per unit volume of a substance?

• Gravity

• Density

• Pressure

• Volume

Answer explanation

Density is the measure of mass per unit volume of a substance. It describes how tightly packed the particles are in a given space.

Which of the following is not an example of convection?

• Boiling water in a pot.

• Temperature changes in ocean currents.

• Ice melting in your hand.

• Wind blowing from the sea to the land.

Answer explanation

Convection involves the transfer of heat through the movement of fluids. Boiling water, ocean temperature changes, and wind blowing from the sea to the land are all examples of convection. However, ice melting in your hand is not an example of convection as it is a result of heat transfer through conduction.

Tags

NGSS.MS-ESS2-6

Which of the following is an example of heat transfer by conduction?

• Heat from a stove is transferred to a pot.

• Heat from the sun warms the surface of the earth.

• Warm air rises, causing cooler air to move in and replace it.

• Heat from the earth's core causes magma to rise to the surface.

Answer explanation

Heat transfer by conduction occurs when heat from a stove is transferred to a pot of water.