Science tip: Friction is independent of the surface area! It may sound counter-intuitive, since increasing the contact area would create a larger source of frictional forces. However, it also reduces the pressure between the two surfaces for a given force holding them together. Since pressure equals force divided by the area of contact, it works[…]
Science tip: Another question from a reader. This is a Crookes radiometer. It is not in syllabus but the student is expected to be able to infer from the description and diagram. ( https://en.wikipedia.org/wiki/Crookes_radiometer ) The answers are: (a) chemical energy (from inside the batteries) -> electrical energy (the electricity) -> light energy (from the[…]
Science tip: "Force" and "Energy" mean different things. Force is a push or a pull on an object, and can cause an object to change its momentum (different direction or speed). Energy is the capacity to do work. Energy has a few forms in the syllabus – electrical, gravitational potential, kinetic chemical, light, heat, sound.[…]
Science tip: It’s a common misconception that the white mist coming out of a kettle is steam. This has appeared in the PSLE a few times. We commonly call the white mist steam – and most people will agree on that term. In science, however, steam is considered to be the hot water vapour released[…]
Science tip: Words like "populations", "community", "consumers" and "producers" are specific scientific terms in biology and PSLE Science. Although we don’t use these terms if we’re not an ecologist, it is important to learn these in order to ace your Science exam. Population: a group of plants and animals of the same kind, living and[…]
Science tip: qn: "my gal asked if evaporation will be faster with wind. I answered "Yes" but am stuck when we have to explain why?" ans: When water evaporates, the water molecules are released into the air. Water molecules can also go back from the air into the water. When humidity is at 100%, the[…]
Science tip: Qn: "A test-tube filled with some water is placed in a beaker containing some ice. If salt is added to the ice, the water in the test-tube will freeze. But I thought salt will lower the freezing point of water and hence the ice in the beaker will melt? Isn’t that the reason[…]
Science tip: Qn: Camel can drink large amount of water at a time and it has capacity to stay long without water in hot dessert. Is this structural adaptation or behavioral? Ans: Its mostly structural rather than behavioural. The Kangaroo Rat is an interesting animal that can illustrate both structural and behavioural adaptations. Structural: they[…]
Science Tip Ace the MCQ! The MCQ comprises 30 questions with 2 marks each and will contribute 60% to the final grade. A student aiming for A* should try to get full marks on this section. Some students do not realise the importance of the MCQ and make careless mistakes or jump too quickly to[…]