Question 1:
Concrete is an example of composite material that has been used since ancient times.
(a) What is the meaning of composite material?
(b) Is concrete suitable to be used to build the pillars of buildings? Explain.
(c) Explain how concrete may be reinforced.
(d) State two uses of reinforced concrete.
Answer:
(a) Combination of two or more non-homogeneous substances
(b) Not suitable. Concrete is resistant to compression but is brittle due to its weak stretching strength
(c) The stretching weakness of concrete can be strengthened by inserting steel rods in concrete. The steel rods are not brittle because it can withstand stretching.
(d) To build bridges and buildings
Concrete is an example of composite material that has been used since ancient times.
(a) What is the meaning of composite material?
(b) Is concrete suitable to be used to build the pillars of buildings? Explain.
(c) Explain how concrete may be reinforced.
(d) State two uses of reinforced concrete.
Answer:
(a) Combination of two or more non-homogeneous substances
(b) Not suitable. Concrete is resistant to compression but is brittle due to its weak stretching strength
(c) The stretching weakness of concrete can be strengthened by inserting steel rods in concrete. The steel rods are not brittle because it can withstand stretching.
(d) To build bridges and buildings
Question 2:
Fibre glass is made by immersing glass fibre in molten plastic.
(a) Name the matrix substance and strengthening substance used to make fibre glass.
(b) Explain why fibre glass is suitable to be used to make water storage tanks.
Answer:
(a) Matrix substance: plastic; Strengthening substance: fibre glass
(b)
• Has high strength-weight ratio
• Strong and durable (resistant towards compression and stretching forces)
• Does not pollute the water that it stores (chemically inert)
• Low building cost
Fibre glass is made by immersing glass fibre in molten plastic.
(a) Name the matrix substance and strengthening substance used to make fibre glass.
(b) Explain why fibre glass is suitable to be used to make water storage tanks.
Answer:
(a) Matrix substance: plastic; Strengthening substance: fibre glass
(b)
• Has high strength-weight ratio
• Strong and durable (resistant towards compression and stretching forces)
• Does not pollute the water that it stores (chemically inert)
• Low building cost
Question 3:
Optical fibre has replaced copper wire in the transmission of information and data.
(a) Name three structures that make up an optical fibre.
(b) How does optical fibres transmit information and data?
(c) Compare the usage of optical fibres and copper wires in high definition cable TV network.
Answer:
(a)
• Protective jacket
• Sheath layer
• Core
(b) To transmit information and data in the form of light reflection
(c)
Transmission of high definition cable TV needs
• High capacity
• High speed
• High band width
Fibre optics use light that can send information faster than copper wire. Fibre optics have wider band with compared to copper wire.
Optical fibre has replaced copper wire in the transmission of information and data.
(a) Name three structures that make up an optical fibre.
(b) How does optical fibres transmit information and data?
(c) Compare the usage of optical fibres and copper wires in high definition cable TV network.
Answer:
(a)
• Protective jacket
• Sheath layer
• Core
(b) To transmit information and data in the form of light reflection
(c)
Transmission of high definition cable TV needs
• High capacity
• High speed
• High band width
Fibre optics use light that can send information faster than copper wire. Fibre optics have wider band with compared to copper wire.
Question 4:
Photochromic glass is a composite material which is always used to make car windows.
(a) State the main component in photochromic glass.
(b) Which component in 4(a) is sensitive to UV light?
(c) State two other uses of photochromic glass.
Answer:
(a) Glass, silver chloride and copper(I) chloride
(b) Silver chloride
(c)
• to make building windows
• to make camera lenses
Photochromic glass is a composite material which is always used to make car windows.
(a) State the main component in photochromic glass.
(b) Which component in 4(a) is sensitive to UV light?
(c) State two other uses of photochromic glass.
Answer:
(a) Glass, silver chloride and copper(I) chloride
(b) Silver chloride
(c)
• to make building windows
• to make camera lenses