SHCCES_P6_SCI_2TERM_EXAM_Ch4

Humans invent machines to make life ​ (a)   .Different kinds of​ (b)   are used to drive ​ (c)   .

• easier
• power
• machines
• more difficult

People in the past invented different machines to make their work easier. what drives these machines?

• god

• animals

• humans

• fire

• wind

How do machine help people ?

Machines save man power. They increase (?) and efficiency.

How do machine help people ?

Machines save man power. They increase productivity and (?).

The steam engine:

• It neesds manpower.

• It drives other machines.

• It works in indoor with sunshine

The steam ​ (a)   when water ​ (b)   makes the paper windmill ​ (c)   .

• given off
• boils
• move

Steam is very ​ (a)   . Don't get too ​ (b)   it!

• hot
• close to
• cold
• far away

Oldsteam engine

After the steam has lifted the piston,the cylinder has to be cooled for thepiston to fall back down.Then,thecylinder has to be heated again to liftthe piston. It is inefficient and wastesa lot of time and fuel.

蒸汽將活塞舉起後，必須冷卻氣缸以使活塞回落。然後，必須再次加熱氣缸以舉起活塞。 它效率低下，浪費大量時間和燃料。

How James Watt improved the steam engine

I'll make a more efficient steamengine which removes the steam oncethe piston has been lifted. This way,the cylinder can cool more quicklyand the piston can keep operating.

我會製造一個更高效的蒸汽機，一旦活塞被舉起，它就會排出蒸汽。 這樣，氣缸可以更快地冷卻，活塞可以繼續運行。

Old steam engine:
It uses ​ (a)   fuel.Its efficiency is ​ (b)   .

• a lot of
• low
• less
• high