Materials - Answers
[ Question Paper ]They used three spoons - a wooden spoon, a metal spoon and a plastic spoon.
They attached a small plastic bead to the spoon handle with a blob of margarine. Then they put each spoon in a beaker of hot water, with the handle out of the water.
Here are their results.
| Spoon | Margarine melted and bead slipped off the spoon (Minutes and seconds) |
| metal | 4 min. 20 sec. |
| wooden | Bead did not move after 15 min. |
| plastic | Bead started to melt after 8 min. |
The heat from the water passed through the metal spoon more quickly than through the other spoons because metal is a good conductor of heat. / When the heat passed through the spoon, the margarine melted and the bead fell off.
Because wood is not a good conductor of heat and so
the handle doesn't get hot when you are stirring hot food.
The metal of the saucepan is a good conductor and
retainer of heat. The heat from the metal saucepan is transferred to
the contents of the pan, and so the food heats up more quickly.
Metal is a good conductor of heat. If the handles of the saucepans were made of metal, they would become too hot to hold and that would be dangerous. Someone trying to hold a metal handle could drop the saucepan or receive a nasty burn.
A wooden block was pulled across a smooth wooden tray using a forcemeter until it was moving at a steady pace. When the block was moving steadily, the forcemeter read 6 newtons. Different materials were placed in the tray and the experiment was repeated.
| Material in the tray | Forcemeter reading in newtons |
| smooth plastic | 4 |
| glass | 3 |
| corrugated paper | 7 |
| heavy duty carpet (e.g.. from a doormat) | 10 |
| small pebbles | 9 |
When the gymnast's hands are rubbing against the apparatus, there is a lot of friction. This means the gymnast's hands get hot and start to sweat and the gymnast cannot move freely. The chalk powder helps to keep the hands cool and stop them from sweating.
Put a circle around the correct answer:
| Which material will dissolve in water to make a solution? | |||
| sand | sugar | soil | stone |
| To separate the salt from the water in a salt solution, you can leave the solution to stand in a container for a few days until the water | |||
| freezes | dissolves | evaporates | melts |
| When ice is placed in water it | |||
| melts | freezes | condenses | evaporates |
| When steam from a boiling kettle reaches a cold window, the steam turns into | |||
| a solution | condensation | ice | water |
