Spencer: Alice is writing a book for Engineering students. So, Alice, the key question: What’s the point of your book?
Alice:
I want students to notice engineering principles in practice all around them – I mean, in their everyday life. I want them to ask questions all the time. What does that machine do? How does it work?
Spencer:
So how important are engineering principles to everyday life?
Alice: Well, they’re a basic part of everything we do. Spencer: Even walking? Alice:
Absolutely. There are engineering principles in walking, but I’m really more interested in machines in everyday life.
Spencer: OK. So, can you give us an example? Alice:
Spencer: Alice:
Yes, of course. In my book, I talk about the engineering principles in the design of roller coasters.
Roller coasters? Why do you talk about roller coasters?
Because they show basic principles of engineering.
Spencer: Really? How many basic principles? Alice: Well, three, actually. Spencer:
Alice: Alice:
That’s good! Not too many to remember! So what’s the first principle?
It’s probably very obvious. It’s this: Gravity pulls everything down towards the Earth.
Spencer: OK. Gravity pulls everything down, but how does gravity apply to a roller coaster?
Well, roller coasters have lots of down slopes. We can use gravity on the down slopes as the energy source.
Spencer: What about the up slopes? We can’t use gravity on them.
Alice: Alice:
No, so we must have more down slopes than up slopes.
Spencer: How can we have more down than up? It’s impossible.
Not really. We start with a big up slope. It’s called the lift hill. Machinery pulls the roller coaster car to the top of this hill. But after that, the car does not have an energy source except gravity.
Spencer: So how does it get up the hills? Alice:
Spencer: Can you say that again?
That’s the second principle: The conservation of energy. We cannot create energy or destroy it. But we can change it.
Alice:
Yes, we cannot create energy or destroy it. But we can change it. The machinery pulls the roller coaster to the top of the lift hill. It uses mechanical energy and turns it into potential energy.
Spencer: What does potential energy mean? Alice:
It becomes kinetic energy … movement energy.
It is the ability to do work. The roller coaster car at the top of the hill accelerates with the force of gravity.
Spencer: And the potential energy becomes …? Alice:
Spencer: And the kinetic energy moves the car up to the top of the next hill?
Alice:
Exactly. The car decelerates, but it reaches the top and the whole process begins again.
Spencer: De … decelerates? Alice: Yes, it slows down. Spencer: OK. So that’s gravity and the conservation of energy. What’s the final principle?
Alice:
Well, it’s to do with the final bit of the roller coaster. How does the roller coaster stop?
Spencer: Does it have brakes? Alice: Not really, because it doesn’t have a driver. Spencer: So it should just keep on going … Alice:
Spencer: Why does it stop? Alice:
… But it stops. It stops by the entrance, so people can get off and more people can get on.
That’s the final principle: Friction. All moving things experience friction. On the roller coaster, friction comes from the air around the car, and from the roller coaster track, and from the axles of the roller coaster car and so on.
Spencer: I understand … I think. 068
Unit 5, A problem-solving approach Exercise F
Listen to Part 2. Spencer:
So we’ve talked about three engineering principles – gravity, conservation of energy and friction, but why is it important for students to look for engineering principles in everyday life?
Alice:
Well, I think there are two reasons. Firstly, engineering is about everyday life! It is not an academic study – I mean, something you just do at university.
Spencer: OK. So students need to understand this? Alice: Yes, it’s essential. Spencer: Why? Alice:
Because, secondly, engineering is about solving problems. So students need to develop a problem-solving approach to life.
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