## Back to school: the answers

Posted on Sunday 17 August 2008 at 1:40 pm by Jacob Aron
In Education

As promised, here are the answers to yesterdays test set by the Telegraph.

1 19.3g per cm³

I was correct, but shouldn’t have bothered with multiplication factors.

2 c) 3 d) 4 b) 5 c) and d)

All correct.

6 a) Mr Dadier eats a bowl of spaghetti and goes for a run – transfer of chemical into kinetic (and heat) energy.

I got this one. Any transfer of energy will produce heat energy as waste, because no transfer is 100% efficient, which is why I didn’t include it in my answer.

b) A pendulum inside a grandfather clock swings back and forth – gravitational potential energy being changed into kinetic energy and back again.

Oh dear. I said elastic rather than gravitational potential. A classic case of not reading the question properly. I saw “clock” and thought of a wind-up, not a pendulum.

c) A football is kicked towards goal, hits the crossbar and bounces back off – gravitational potential, kinetic, elastic potential and kinetic again.

Bit confused by this one. Presumably the ball is flying up, in which case kinetic energy is converted to gravitational potential energy, not the other way round. It could be that they are setting their zero level for gravitational potential energy somewhere silly (i.e., not the ground).

7 It is colourless

Score one for random guessing!

8 c) 9 a) 10 a)

All correct, although 9 and 10 were perhaps guesses as well.

11 The moment at which a falling body ceases to accelerate.

Going to have to disagree with the Telegraph. Terminal velocity is by definition a velocity, not a point in time. However, terminal velocity is reached at the moment a falling body ceases to accelerate.

12 Cold can’t seep into bones – it’s the heat leaving your body that makes you cold. Absolute zero can never be attained.

Pretty much exactly what I said.

13

Oh dear. No diagram for the question, and now no answer. Get on it, Telegraph webmasters!

14 a)

My slightly verbose answers was correct.

15 78% nitrogen, 21% oxygen and 1% other gases

That’s what I said, just without the specifics. It seems I did pretty well then, getting all of the answers except for some of question 6. I guess I’d better brush up on energy transfer! Whilst I do that, be sure to check back later today for a “proper” roundup post.

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