Heat transfer (2)

Which statement explains how sweating helps regulate body temperature during exercise?

• Sweat reflects sunlight, preventing heat from entering the body.

• Body heat is used to evporate sweat into water vapour, and the person cools down during the process.

• Sweat increases blood flow to the skin, warming the body.

• Sweat absorbs body heat and drips off, reducing excess warmth.

Which example involves thermal radiation as the primary mode of heat transfer?

• Heating up air in the hot air balloon

• The interior of a car becoming hot after being parked outside all day.

• A hot frying pan heating oil placed in it

• A hairdryer warming your hands with hot air

Why do people often wear light-colored clothing in hot, sunny weather?

• Light colors prevent conduction from the air

• Light colors absorb more radiation from the sun

• Light colors are poor absorbers of radiant heat from the Sun

• Light colors increase the body’s rate of evaporation

Why do astronauts in space rely on radiation for heat transfer instead of conduction or convection?

• Space is too cold for conduction to work

• There are no particles in space to transfer heat by conduction or convection

• Convection only works in low-gravity environments

• Radiation only happens in a vacuum

Why do thermos flasks have a shiny inner surface?

• To absorb heat from the outside

• To reduce heat transfer by conduction

• To reflect radiant heat and reduce radiation loss

• To allow heat to escape efficiently

Choose all the factors that affect the rate of heat conduction of an object

• colour of the object

• thermal conductivity of the material of the object

• surface area of contact between the object with the other object

Choose all that occur during convection.

• • Heat transfer through direct contact between particles

• • Fluid movement due to density changes

• Heat transfer via electromagnetic waves

• • Hot fluid rises and cool fluid sinks

Choose all that affect the rate of heat transfer through radiation of a surface of an object

• Surface area exposed

• The color of the surface

• The roughness/smoothness of the surface

• The dull/shininess of the surface

_______________ describes the rising and sinking of fluids of different temperatures and densities.

Choose all that are correct:

The thermal conductivity of a material determines how easily heat can be transferred by __________.

• radiation

• conduction

• convection

• insulation