Desirable Material Properties of various objects help

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Alexandramartis
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Hello, I have a selection of questions below concerning the material properties of different objects. I have answered all of the problems below but would appreciate some advice upon my given answers and justifications, I would be tremendously appreciative if anyone could offer possible improvements.

Using the proper scientific terms, describe the desirable properties of materials used for the following:

1. A rope for a mountain climber- should have a high tensile strength, being the resistance of a the rope to breaking under tension of the climber's weight.

2. A hammer; Arguably, a hammer should be hard, the property that it is resistant to pressure and resists dents, scratches, and other permanent changes under compressive force.

3. A dinner plate- should have a great hardness, referring to the property of a the material to resist pressurised scratching or indention by sharp objects, e.g. cutlery and the force eating accompanies over time.

4. An electric cable to a lawnmower - should have a high conductivity, being the measure of the ease at which an electric charge or heat can pass through a material. A conductor is a material which gives very little resistance to the flow of an electric current. But this does not answer the question suitably, since it concerns the electric cable not just the metal wiring. Should I be considering the malleability of the cable, being the substance's ability to deform under pressure or rather its ability to be reshaped when unravelled.

5 - A bicycle frame - The main property of importance for bike frame design is Young’s Modulus. This describes the material’s stiffness – the tendency for it to return to its original shape under load by resisting deformation by tension or compression. Young’s Modulus is similar for metals made from the same alloy. Repeated loading of materials can lead to fatigue failure, therefore, designing frames to minimise the maximum stress levels experienced, the lifetime of the frame will be more than long enough to suit expected usage.

6- A prothetic hip joint - should be strong, the ability to resist both deformation and failure by withstanding an applied stress that may come from the movement of everyday life while continuing to support the person.

7. A helmet for a cyclist - should be strong, being is the ability of a material to resist both deformation and failure. Or rather should it be shock-absorbing (but I do no think that this is a "proper scientific term" as specified).
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Alexandramartis
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Hello, sorry to ask but I am still not entirely sure how to answer these problems. I do not know whether the terms I have employed are what the queston specifies by "proper scientific terms" and would be appreciative if anyone could offer some guidance 😊👍
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Joinedup
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7 energy dissipative is perhaps an upgrade on shock absorbing

it's also an important factor in mountain climbing rope... because the rope has stop the climber safely after a period of free-fall and stopping quickly because you've got a stiff rope isn't necessarily much better than stopping quickly because you've hit the ground. for example https://youtu.be/yR17BgK8LfE?t=142 you can see the climber reaches the end of the rope and then decelerates for another couple of meters.

A lot of these products are composites of more than one material and IMO you should be saying something about all the obvious materials... e.g.include the insulating sheath on the lawnmower cable... you could also say that for flexibility the copper in the cable is drawn into many thin wires which are paralleled up to achive the required cross sectional area. The hammer usually has a handle on it made of a different material, fiberglass (by which we mean a composite of glass fiber and a thermosetting resin) or wood - have a think about why that might be.

You could also IMO be picking up a lot more pretty obvious properties of those items - dinner plates want to have a shiny, impervious surface to make them easy to clean and reuse.
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Alexandramartis
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(Original post by Joinedup)
7 energy dissipative is perhaps an upgrade on shock absorbing

it's also an important factor in mountain climbing rope... because the rope has stop the climber safely after a period of free-fall and stopping quickly because you've got a stiff rope isn't necessarily much better than stopping quickly because you've hit the ground. for example https://youtu.be/yR17BgK8LfE?t=142 you can see the climber reaches the end of the rope and then decelerates for another couple of meters.

A lot of these products are composites of more than one material and IMO you should be saying something about all the obvious materials... e.g.include the insulating sheath on the lawnmower cable... you could also say that for flexibility the copper in the cable is drawn into many thin wires which are paralleled up to achive the required cross sectional area. The hammer usually has a handle on it made of a different material, fiberglass (by which we mean a composite of glass fiber and a thermosetting resin) or wood - have a think about why that might be.

You could also IMO be picking up a lot more pretty obvious properties of those items - dinner plates want to have a shiny, impervious surface to make them easy to clean and reuse.
Thank you for your reply and your advice. I have added to some of my answers below in bold to show any new thoughts I had to add.

1. A rope for a mountain climber- should the rope have energy dissipative properties as opposed to a high tensile strength? Or rather should this property take predominance since a you have shown the rope has stop the climber safely after a period of free-fall?

In regard to composite materials like the hammer, would multiple materials be chosen for components to factor in reducing the weight for the objects relative stiffness and strength. However, they maintain a high impact strength which gives them an excellent strength to weight ratio.

3. A dinner plate - should have a great hardness, referring to the property of a the material to resist pressurised scratching or indention by sharp objects, e.g. cutlery and the force eating accompanies over time. Moreover, dinner plates should again have a high strength to weight ratio, wherein, although the objects are light to accommodate everyday usage they have strong and impervious surfaces which can withstand applied pressure. The surface of the plates should be shiny and resistant to spoilage to ensure they are easy to clean and reuse.

4. An electric cable to a lawnmower - should have a high conductivity, being the measure of the ease at which an electric charge or heat can pass through a material. A conductor is a material which gives very little resistance to the flow of an electric current. But this does not answer the question suitably, since it concerns the electric cable not just the metal wiring. Should I be considering the malleability of the cable, being the substance's ability to deform under pressure or rather its ability to be reshaped when unravelled. The insulating sheath should be elastic and able to bend and return to its original shape. Additionally, the insulation should have ability to withstand pulling or stretching force, a high tensile strength, to complement overall durability, to withstand wear and tear through regular usage. The outer insulation should also be able to withstand environmental attack and decay, e.g. how some plastics have been developed to withstand hostile environments like how uPVC is resistant to the effects of UV light which would quickly cause normal PVC to become brittle. A range of coatings and surface finishes could be applied to enhance the corrosion resistance of the insulating sheath.

5 - A bicycle frame - The main property of importance for bike frame design is Young’s Modulus. This describes the material’s stiffness – the tendency for it to return to its original shape under load by resisting deformation by tension or compression. Young’s Modulus is similar for metals made from the same alloy. Repeated loading of materials can lead to fatigue failure, therefore, designing frames to minimise the maximum stress levels experienced, the lifetime of the frame will be more than long enough to suit expected usage.

6- A prothetic hip joint - should be strong, the ability to resist both deformation and failure by withstanding an applied stress that may come from the movement of everyday life while continuing to support the person.

7. A helmet for a cyclist - should be strong, being is the ability of a material to resist both deformation and failure. Or rather should it be shock-absorbing (but I do no think that this is a "proper scientific term" as specified).

I am not sure how to elaborate or correct the other objects?
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wilson fafa
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yeah that is it do your s for urself
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Joinedup
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I'll give you my ideas about this sort of question.

It seems like a research and report type question - you don't necessarily have to know a lot about the different objects to start with. The question wants you to find out on the internet (or elsewhere) what the properties required are... there can be several properties per item and write a sentences or two about why the materials used are suitable.
Some of those objects have several obvious parts made out of different materials. That happened for a reason and you need to explain what the reasons for those choices are.

This sort of question usually has a word limit because there's almost no limit to the amount of information that you can find out, even about familiar objects... finding tons of information is almost the easy part *... editing it down so that you hit the word limit without losing the most important information is the difficult bit and you learn how to do it by writing drafts, reading them back and then writing the bits that seem like they could be better again differently until you are happy with it.

Every object that is not produced by nature has had some thought put into the materials and techniques used to make it - nothing just happens for no reason. sometimes a new material will come along and be superior to a more traditional material and begin to replace it in newly produced items - I'm especailly thinking of wood being replaced by fiberglass in tool handles


Some of the objects are pretty mundane household objects that have basically been made of the same material for centuries - I'm thinking of dinner plates... in which case you might not find so much on the internet because they 'hide in plain sight'... however in that case you can think about everything that object has to do in normal use.

Certainly it doesn't seem difficult to find lots of information about exotic objects like hip replacement - these are relatively new and 'sexy' the people making them are proud of what they do and want to tell people about it - the surgeons putting them in also want the public to not be mystified about what's happening


* Michael Faraday quite famously gave a series of 6 lectures about a candle at the Royal Institution
* Leonard Reed wrote a book about making pencils (from an economics perspective - but the various materials and processes involved are talked about)
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Pangol
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(Original post by Joinedup)
I'll give you my ideas about this sort of question.

It seems like a research and report type question
Not an unreasonable assumption at all, from the way that the question was described originally. But recognising where the question comes from, and therefore knowing how many marks there are for each part, it is a little more basic than that.

(Although there are some small differences between this version I have found and the question in the first post, so it may be that more is required.)

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Joinedup
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(Original post by Pangol)
Not an unreasonable assumption at all, from the way that the question was described originally. But recognising where the question comes from, and therefore knowing how many marks there are for each part, it is a little more basic than that.

(Although there are some small differences between this version I have found and the question in the first post, so it may be that more is required.)

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Yeah not surprisingly it's useful to see the original question and know the number of marks available.
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