RI: OK and that quite nicely explains the fact that they’re going / one’s going faster than the other. Em OK and again
tell about what might happen when this toboggan reaches the ground and you know as we know it’ll slow down –
T5: – so on the flat?
RI: Yeah what’s happened to the energy then?
T5: OK so say toboggan A reaches the bottom. When toboggan A reaches the bottom, em, er assuming that it is on a
surface which is in any way rough or involves any kind of em, er where there may be frictional forces that are withhold /
holding it back and even if there aren’t then there’ll be air resistance but either way, em, then it will be losing it’s er
kinetic energy that it had, which it had gained from the GPE. It now starts to lose em, in overcoming friction and that
energy is heating up the toboggan rails and the ground, and making a bit of noise er and is therefore dissipated and
eventually the toboggan therefore stops. There you go.
Q7. The inanimate nature of toboggans means they can’t have energy.
False
T5: That’s false.
RI: As you said there’s GPE and KE (acknowledgment). Most physicists are quite happy with that.
Q8. Both toboggans have the same energy, if you ignore their friction with the snow and air resistance.
True
T5: The same energy at the top presumably? Do they have the same energy now? They have they same energy sorry
they have the same energy, they do have the same energy that’s true, that’s true –
RI: – again, what are you applying?
T5: Conservation of energy. ‘Cause B has more GPE, and less KE than A and vice versa OK.
Q9. The only energy that the toboggans have comes from their movement.
False
T5: That’s false.
Q10. The toboggan with the smoothest runners is the most efficient.
True
T5: Em; right, that depends on / if you want to go fast or not. Er, assuming that you want to go, the fastest, then the
energy needed is, / I think that’s probably true.
RI: All right. But em, we’ve got various things happening here you’re talking about –
T5: – it depends on what you mean to say efficient. Depends on what you want to get out of it –
RI: – if your goal is to go fast that’s one thing and then another thing is maybe thinking about what / use of the word
efficient as well.
T5: Yeah, so; without specifying what efficient means I don’t think you can answer the question.
RI: Right OK so take a stance on the word efficient.
T5: OK in that case I would say assuming that you want to go as fast as you can which is kind of the point of toboggans,
then if it has the smoothest runners, then more of the energy is being able to turn into, into kinetic energy and not being
lost down the way so, it’s true.
RI: Right, that’s fine. (laughter)
Q11. The energy the toboggans had while moving down the hill has disappeared when they have stopped at the bottom.
False
T5: The energy has disappeared. That’s false –
RI: – treating the words at face value –
T5: – yeah it hasn’t disappeared –
RI: – so what’s better to say?
T5: Has been converted into other forms
Q12. The descending toboggans have force.
False
T5: Well, that depends on, / they have weight certainly, which is a force. So, do they have force? They have / there is a
force between them and the Earth, and between them and various other things. Whether or not they have force -
RI: – a statement like this is an interesting one and I always say that, it’s the sort of thing a pupil might say. You know
and so it’s up to us to try / and you’ve corrected it beautifully by saying that it might be better to say that there is a force
acting on them, rather than they have a force.
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