Electrical System
Adding more batteries in a series connection to a circuit will cause the bulbs in the circuit to become less bright.
False. Adding more batteries in a series connection to a circuit will cause the bulbs in the circuit to become brighter.
Gravitational force and gravitational potential energy increases with the height of an object above the Earth's surface.
False. Gravitational force does not change with its position above the Earth's surface while gravitational potential energy increases as the object's height above the Earth's surface increases.
All things, living and non-living, possess energy.
True
Since plasticine can be moulded to change its shape, it is not a solid.
False. Objects that can be moulded are solid because their shapes only change if a force is applied on them. They have fixed shapes and their volumes do not change.
What is the difference between heat and temperature?
Heat is a form of energy found in objects while temperature refers to how hot or cold an object is.
State two ways we can help to conserve electricity.
Use ceiling fans instead of air conditioner
Switching off the light when no one is in the room
When I swing the magnet, it moves closer to some round magnets and away from others. Why is this so?
The swinging magnet is attracted by some of the round magnets and repelled by others so it moves in an unpredictable manner.
No matter how hard we bounce the basketball, the subsequent bounces get lower and lower. Why is this so?
With every bounce, some of the kinetic energy is converted to other forms of energy such as sound and heat. The ball will come to a stop when it has no energy left.
A bicycle type is fully inflated but Ahmad is still able to pump more air into it. Why is this possible?
Air does not have a definite volume / Air can be compressed
The alcohol swab feels cool when it touches my skin. Why is this so?
The alcohol takes away some heat from the skin when it evaporates, thus leaving behind a cooling effect.
Why is it important to have a circuit breaker in the house?
A circuit breaker helps to break the circuit in the house and prevent any fire from breaking out if a large current accidentally flows through.
Why do we need to put on shoes with smooth soles when we are on the bowling lane?
Our walking shoes are likely to have some particles in the grooves of the soles. Due to friction, these particles can cause damage to the smooth flooring of the bowling lane. Hence, we need to wear shoes with smooth soles.
A light ray bends as it passes through air and water. What happens to the light ray when it passes through glass?
When light ray passes from the surroundings into the glass, its path is bent inwards. When the light ray passes through the glass to the surroundings, its path is bent outwards.
Which of the following statements about condensation and evaporation are correct?
A - Both processes involve a change in state
B - Both processes do not occur at fixed temperatures
C - One process involves heat gain while the other involves heat loss.
A, B and C
At many coffee shops, thick ceramic cups instead of metal cups are used to serve coffee. Why is this so?
Ceramic is not a good conductor of heat. Heat in a thick ceramic cup will take a longer time to pass through the cup to your fingers. This means that the drink would be able to stay warm longer in a ceramic cup than in a metal cup. It also means that you would be able to hold the cup comfortably while slowly sipping your hot drink.
How is a rainbow formed?
When light rays pass through rain drops, each rain drop acts a a prism and splits them into seven different colours. The rainbow that we see is the reflection of the split coloured rays.
Mum said we have to wrap the vegetables in newspaper before storing them in the fridge. Why is newspaper used?
Newspaper will absorb the water vapour given out by the vegetables. This helps to keep the vegetables dry and prevent them from turning soft and limp.
I have two bags of ice. Each bag of ice is made up of the same amount of water. Bag A contains one ice block while Bag B contains several ice cubes. Which bag of ice will melt completely faster? Why?
The ice cubes in Bag B will melt faster. Heat gained by the ice cubes is faster because the total exposed surface area of all the ice cubes is greater than the surface area of the ice block.
A man is rappelling down a mountain. He stops to take a rest. John says, "Since the man is resting, he does not need any energy. He also does not have any energy." Is John correct? Explain.
No. The man possesses energy even when he is resting. He possesses chemical potential energy and gravitational potential energy.
The rock has been cracked by ice. How is this possible?
Water flows into small gaps in the rock. When it freezes into ice, it expands and thus occupies more space. The ice pushes against the sides of the rock and cracks it.
John is having a hot bowl of soup noodles for dinner. He added some water at room temperature to his noodles. What will happen to the temperature of the soup? Explain.
The temperature of the hot soup will decrease. The hot soup loses heat to the water and the water gains heat from the hot soup. As the soup loses heat, its temperature decreases.