Making a Newton's Cradle

[Frank Erskine]

[Bob Eager]

At least they're not the size of bowling balls.

[Matty F]

Empty cistern float balls bounce really well. I might just use those thanks.

[Chris J Dixon]

Salford had one in the (now demolished) Chemistry Tower. Chemists had to be dissuaded from leaping aboard with arms full of glassware.

Chris

[Chris J Dixon]

Ah, the heady days of the sixties. The architects at Salford had provided a bench seat on each floor immediately opposite the paternoster. The place was full of female language students, hemlines were very high, and as the car rose, you popped up at floor level. Views in the tower block were exhilarating.

Going over the top, though frowned upon _had_ to be done. It was a little unnerving, as it got noisier and there was a bit of vibration, being near the drive motors, but not actually as hazardous as getting on and off normally. On each floor there was a hinged flap. so that overhanging feet were not chopped. As the top area was solid, there was a flap with switch to trip the drive, which happened regularly.

Some wag went over the top and emerged standing on his head.

Chris

[Huge]

[Huge]

The whistling from the finger holes? Kewl, isn't it?

[Jules Richardson]

What,

?

Maybe they come in "elephant size" :-)

[whisky-dave]

and no seat belts for anyone...........not even kids.

.

[whisky-dave]

Ping-pong table tennis balls, easy to thread string through. Be even more fun to put a small magnet inside.

Gob stoppers, although they're probably too dangerous as they can be swallowed. Maybe some beads from an old necklace.

[Andrew Gabriel]

ISTR the solar furnaces in south france and spain use either liquid sodium or liquid sodium chloride, I can't recall which. These line a south facing hillside with motor driven mirrors, which all point the sun onto one spot on a tower, where the heat is extracted. One of the ones I looked at had burn marks around the concrete structure where the aiming had missed the point. It did occur to me that there was no provision for an emergency shutdown if the motor drives failed, even a roller blind to release over the mirrors would have done.

One of the other ones had several large steel artifacts dotted around the car park, such as giant engine blocks, which they'd hung at the focus and melted for the amusement value.

[Andrew Gabriel]

Paternoster, as others have said:

had one in the GEC building on the A1 at Borehamwood (don't know if it's still there - not listed on the web page above). As it went round the top or the bottom, you could do a handstand so it looked like the lift car got turned upside down - designed to instill confidence in someone standing outside who'ed never used it before and was plucking up courage to step in for the first time, NOT;-).

I recall one occasion when I was in the lift, and a window cleaner stepped in with his stepladder and bucket. We could all see the ladder was somewhat longer than the lift and we lept out. Sure enough, it jammed when it had gone up half a floor.

It had very sensitive hinged landing platforms which tripped it off very easily if someone misjudged getting on or off, so it spent half it's time waiting for the building maintenance folks to come and switch it back on.

[Andrew Gabriel]

Snap - was that a factory in Guidford Street, roughly opposite Bridge Street? I used to walk past it.

[Huge]

Sodium boils at 883 deg C, so almost certainly the latter. NaCl melts at 801 degC, although that can be reduced by mixing it with CaCl.

[Tim Watts]

Wait... If each ball contained a pair of rare earth magnets such that each pair of balls touched S-S or N-N, that could be very funky. A non contact Newton with perfect elasticity.

I wonder how it would behave as the balls would not be touching in a normal setup? I can see the basic effect working, ie the end bals go flying off. But there might be some interesting secondary effects on the middle balls.

[Tim Watts]

They have Inertial Dampeners, just like the 3rd Doctor's car (Bessie?).

That would be weird: hit a tree, come to a near instaneous dead stop and not feel a thing?

[Tim Watts]

It *could* have been something like that. They did do alternative energy research.

[Reentrant]

There was a Paternoster in the Attenborough Building at Leicester University in the 70's. You could go round the top and bottom with no problem - it was just dark. A good trick during fresher's week was to stand on your head as you went round the bottom and reappeared at the ground floor.

[Perry (News)]

On Tue, 01 Jun 2010 17:17:31 +0100, Bruce waxed lyrical about:

We used to have one when I was at Imperial (early 80s), a pair of shafts, one side went up, the other down, I seem to recall it was in the Chem buildings near the Library/Queen's Tower

It used to be fun persuading the freshers to go 'over the top', if only because I remembered how unnerving the experience was when I was persuaded to do it (after a couple* of pints of Fullers)

• defined as a number between 2 and several

[geoff]

He already mentioned ball and chains in the previous sentence