WS8.2a Energy Transfer (Conduction & Convection)

In a BBQ, the metal tongs left on the pit can become too hot for us to hold because of _____.

In a BBQ, the air above the pit can become so hot that when a wind blows the hot air towards us, because of _____.

In a BBQ, we feel warm even before we reach the barbeque pit, because of _____.

Materials that can transfer energy quickly by conduction are _____.

• good thermal conductors

• poor thermal conductors

• good thermal insulators

• poor thermal insulators

Conduction is a process of energy transfer where energy is transferred through the passing on of vibrational motion from one particle to another. In general, ____ are better conductors and among them, ____ are the best conductors.

• liquids and gas,

  wood

• liquids and gas,

  metals

• solids,

  wood

• solids,

  metals

Conduction in solids are better than through liquids and gases because the particles in liquids and gases _____ than those in solids.

• have stronger intermolecular forces

• have weaker intermolecular forces

• are closer

• are further

Metals are better thermal conductors than non-metals because of _____ that move very fast _____ the metal and transfer energy easily to the particles.

• particles,

  around

• particles,

  through

• free electrons,

  around

• free electrons,

  through

A cardboard cup sleeve is a poor conductor mainly because

• paper is poor conductor

• it has sleeves containing air which is a poor conductor

• paper is poor conductor and has sleeves containing air which is a poor conductor

Convection only occurs in

• solids

• liquids

• gases

During convection, when a liquid is heated, it _____. As a result, its density ____________.

• expands and increases in volume,

  increases and sinks

• expands and increases in volume,

  decreases and rises

• contracts and reduces in volume,

  increases and sinks

• contracts and reduces in volume,

  decreases and rises