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LC Off Topic Thread (2015/16)
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DublinArnie wrote: »Certain engineers would work with physics though?
Yes but there's a big difference between an Engineer and a Physicist, just like how there's a big difference in their Undergrad degree. Saying that, my Physics degree is much more Industry based than a say PASS degree or TP, so it's closer to Engineering in that way.
My friend doing Engineering said they use Physics in a different way e.g Mechanics whereas I study the Measurement and Properties of Matters sort of thing.
Look at it like this...
Physicists are generally paid to discover, document, or explain new physical phenomena. Engineers are generally paid to design marketable products which make use of such phenomena.
However, what we learn is interdisciplinary and many people who do a course like mine essentially end up as Engineers who are less paid (since we wouldn't be accredited). I just learn more in depth stuff than an Engineer. They do Mechanics, I do Quantum Mechanics.
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Lads can any of you help me with my maths? It's about derivatives our teachers gave us this question and told us that for ii) we had to try and find the minimum surface area of the metal. I think this maths is impossible and I have no idea how to get the answers that are in the back of the book!
A cylindrical can is manufactured to hole 1 litre of oil
i) Find the height of the can in terms of the radius, r.
ii) Find the dimensions that will minimise the cost of the metal used to manufacture the can.
The answer for i) is h= (1000) r^-2
pi
and ii) r= (500)^ 1/3 and h= 2(500)^1/3
pi pi0 -
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CookieCat97 wrote: »Lads can any of you help me with my maths? It's about derivatives our teachers gave us this question and told us that for ii) we had to try and find the minimum surface area of the metal. I think this maths is impossible and I have no idea how to get the answers that are in the back of the book!
A cylindrical can is manufactured to hole 1 litre of oil
i) Find the height of the can in terms of the radius, r.
ii) Find the dimensions that will minimise the cost of the metal used to manufacture the can.
The answer for i) is h= (1000) r^-2
pi
and ii) r= (500)^ 1/3 and h= 2(500)^1/3
pi pi
Have you formulated an equation for the surface area?0 -
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S = 2pirh + 2pir^2, yes.
You're only taught to do calculus of one variable in the Leaving Cert but that equation has two variables (r and h). The point of the first part was that you could express that equation only in terms of r.
The quadratic equation for the surface area has a positive coefficient of r^2 which indicates that it looks like the one on the left and not the right in this image i.e. it has a minimum.
Let the first derivative equal to 0 to find the minimum of the curve. You'll get a value for r. That will be one of your dimensions. Then find h.
Ahh! Thank you so much I get it now!
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chocolate98 wrote: »is it just me or is it hard to believe the lc is only 22 weeks away.....
Mocks in 6 weeks for me too
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