8/17/2019 Secondary Two Science Worksheet Effects of Heat 24jan2015

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Date: 24th January 2015

Secondary Two - Effects of Heat

1.0 What is Heat?

Heat is energy that is transmitted from a hotter to cooler region through conduction,

convection and radiation. The differences in temperature beteen the hotter and cooler region

creates a gradient or pathay for heat to flo as shon in the diagram belo.

1.1 Effects of heat in Solids

The flo of heat causes physical changes ithin the matter they flo through. !or e"ample,hen heat flos through a cool steel rod, it causes the steel rod to e"pand. The metal particles

ithin the steel rod, have more energy due to the transfer of heat. Hence the particles are able

to vibrate slightly farther aay from their fi"ed positions. This causes a slight increase in

volume. # RECALL: The particle arrangement in solids.$ Do note, that the nm!er of solid

"articles remain constant !efore and after e#"ansion.

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8/17/2019 Secondary Two Science Worksheet Effects of Heat 24jan2015

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1.' Effects of heat in (i)ids

'ith reference to the diagram above, hen a li(uid is heated, it also e"pands. The e"pansion

is due to the li(uid particles having more energy to move farther apart. This results in an

increase in volume. )onversely, density decreases. Do note that the nm!er of li)id

"articles is constant, *st that the s"acin+ in !etween li)id "articles ha%e increased de

to e#"ansion. 

1. Effects of heat in ases

'ith reference to the diagram above, hen heat is added to a sample of gas molecules, the

gas molecules move faster and collide ith each other more fre(uently. This results in an

increase in pressure and volume. Do note that the nm!er of +as "articles is constant, *st

that the s"acin+ in !etween +as "articles ha%e increased de to e#"ansion. 

*n summary, e"pansion can be termed as an increase in volume, hen heat is applied to

matter. )ontraction occurs hen heat has dissipated aay, resulting in the particles having

less energy. 'ith lesser energy, the particles are unable to vibrate or move farther aay,

hence eventually returning to their pre+heated positions, leading to a decrease in volume.

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