UNDERSTANDING HEAT AND HOW TO ACE SCIENCE TEST – HEAT

What is this topic:

Ans: Heat Expansion

Explain how this happens:

In the day, it is hotter, the surrounding temperature is higher. Since metal is a good conductor of heat, the heat will cause the metal tracks to expand. The gaps are constructed to allow for expansion during the day to prevent buckling of the tracks and causing the train to derail.

Different Materials Used for Different Parts of Cooking Pot

What is this topic:

Ans: Heat Conductors

Explain how this happens:

For cooking pot, heat is required to be conducted from the flame to the base of the pot fast in order to cook the contents in the pot, thus using material like iron, copper etc which are good conductors of heat is preferred. 

As for the handle, since our hands will touch it often and in order not to scald our hands, using material like plastic or wood will be ideal as these materials are bad conductors of heat / insulators and they will conduct heat slower from the pot to the handle and our hand will not be scalded.

What is this topic:

Ans: Heat Travels from Hotter Place to a Colder Place

Explain how this happens:

Iron rod is a good conductor of heat. As the candle is heating the iron rod at one side, the heat will travel along the iron rod from a hotter place to a colder place. Since Thumbtacks  P is nearer to the candle, the wax at P will melt first causing Thumbtacks P to drop first.

UNDERSTANDING MAGNETISM AND HOW TO ACE SCIENCE TEST – MAGNETISM

Objects floating above one another

What is this topic:

Ans: Magnetism

Explain how this happens:

The objects are magnets or have magnets in them. The like poles are facing each other (North pole facing north pole or south pole facing south pole) so they repel each other and float above one another.

Paper clip remains at same position when iron sheet is placed between it and the magnet but floats when iron sheet is being replaced by a wooden plank

What is this topic:

Ans: Magnetism

Explain how this happens:

Although paper clip is a magnetic material, the magnetism or magnetic force of the U-shaped magnet is unable to pass through the iron sheet because iron sheet is a magnetic material, thus unable to attract the paper clip. However magnetism of the U-shaped magnet is able to pass through the wooden plank which is a non magnetic material, thus attracting the paper clip and making it float towards the U-shaped magnet.

Device use for separating iron from sand

What is this topic:

Ans: Magnetism

Explain how this happens:

When the mixture of iron and sand fall onto the belt, they will be carried to the left along the belt since the magnetic wheel is turning anti-clockwise. As the belt travels down towards container X, the sand which is non magnetic material will fall onto container X due to gravity. While the iron which is magnetic material will be attracted by the magnetic wheel as well as the magnet object placed above and between container X and Y. The iron will not fall as the magnetic force is greater than the gravity force acting on them. However once they pass by the magnet object, there is no magnetic force acting on them and they will fall into container Y due to gravity. The process repeats again until all the iron and sand are separated.

Understanding Condensation And How to Ace Science Test – Condensation

Water Droplets On the Outer Surface of Cold Bottle

What is this process:

Ans: Condensation

Explain how this happens:

The warmer water vapour in the surrounding air touches the cooler outer surface of the cold bottle and loses heat to condense into water droplets.

Water Droplets on the underside of the Lid

What is this process:

Ans: Condensation

Explain how this happens:

The warmer water vapour/ steam from the hot content in the pot touches the cooler underside surface of the pot lid and loses heat to condense into water droplets.

Water droplets found on the outer surface of the car window

What is this process:

Ans: Condensation

Explain how this happens:

The warmer water vapour in the surrounding air touches the cooler outer surface of the car window and loses heat to condense into water droplets.

Mist formed Above Pot During Cooking

What is this process:

Ans: Condensation

Explain how this happens:

The warmer water vapour/ steam from the hot content in the pot touches the cooler surrounding air and loses heat to condense into tiny water droplets called mist.

Cloud forming in the Sky

What is this process:

Ans: Condensation

Explain how this happens:

The warmer water vapour rises and touches the cooler surrounding air in the sky and loses heat to condense into tiny water droplets called cloud.