Five of the best for school kids.

http://www.abc.net.au/science/articles/2014/09/03/4079173.htm

Peak Warming Man said:

Five of the best for school kids.

http://www.abc.net.au/science/articles/2014/09/03/4079173.htm

I can still vividly remember one episode of JSM’s show that had me enthralled and perhaps even kicked off my interest in science.

It was a very simple experiment.

Two hour glasses across a weighing scale so they were balanced. He then asked which way would the weighing scale go if one of the hour glasses was inverted.

sibeen said:

Peak Warming Man said:

Five of the best for school kids.

http://www.abc.net.au/science/articles/2014/09/03/4079173.htm

I can still vividly remember one episode of JSM’s show that had me enthralled and perhaps even kicked off my interest in science.

It was a very simple experiment.

Two hour glasses across a weighing scale so they were balanced. He then asked which way would the weighing scale go if one of the hour glasses was inverted.

I recon it wouldn’t move.

bob(from black rock) said:

sibeen said:

Peak Warming Man said:

Five of the best for school kids.

http://www.abc.net.au/science/articles/2014/09/03/4079173.htm

I can still vividly remember one episode of JSM’s show that had me enthralled and perhaps even kicked off my interest in science.

It was a very simple experiment.

Two hour glasses across a weighing scale so they were balanced. He then asked which way would the weighing scale go if one of the hour glasses was inverted.

I recon it wouldn’t move.

It wouldn’t move.

bob(from black rock) said:

sibeen said:

Peak Warming Man said:

Five of the best for school kids.

http://www.abc.net.au/science/articles/2014/09/03/4079173.htm

I can still vividly remember one episode of JSM’s show that had me enthralled and perhaps even kicked off my interest in science.

It was a very simple experiment.

Two hour glasses across a weighing scale so they were balanced. He then asked which way would the weighing scale go if one of the hour glasses was inverted.

I recon it wouldn’t move.

me two

Trick question. It would move, when you pick up the hourglass to turn it upside down.

Bubblecar said:

Trick question. It would move, when you pick up the hourglass to turn it upside down.

Not if both were picked up simultaneously but only one was inverted.

Bubblecar said:

Trick question. It would move, when you pick up the hourglass to turn it upside down.

I’m still thinking I didn’t read the question properly.

The word ‘across” put me off track a bit.

Bubblecar said:

Trick question. It would move, when you pick up the hourglass to turn it upside down.

Lower the beam balance, turn one hourglass over, raise beam balance, no movement.

The inverted one would seem to weigh more because of the added inertia of the falling sand producing a down force on the balance beam on that side in addition to it’s weight.

Skeptic Pete said:

Bubblecar said:

Trick question. It would move, when you pick up the hourglass to turn it upside down.

I’m still thinking I didn’t read the question properly.

The word ‘across” put me off track a bit.

Yes. I originally thought of the glasses being horizontal but realised that wouldn’t change anything.

Once all the potential energy that you gave the sand by elevating it is released it will go back to being in balance with the one on the other side.

Alright, we’ll assume the scales are lockable and have been locked while you turn the hourglass, then unlocked.

Peak Warming Man said:

The inverted one would seem to weigh more because of the added inertia of the falling sand producing a down force on the balance beam on that side in addition to it’s weight.

But what about the weight of the sand in free fall?

The Rev Dodgson said:

Peak Warming Man said:

The inverted one would seem to weigh more because of the added inertia of the falling sand producing a down force on the balance beam on that side in addition to it’s weight.

But what about the weight of the sand in free fall?

Hehe, yes I’m not sure how that would play out.

You can simplify this by considering two 1 tonne blocks of concrete instead of the sand.
Consider them inside a sliding frame, consider the concrete blocks and the sliding frame the hourglass.
Now place them on a beam supported by a fulcrum equal distance from the fulcrum.
Now elevate one of the blocks inside the frame. The system is still balanced, now release the raised block.

I’ll run that through Inventor Simulation when I get some time.

dv is correct, elevating more of the mass causes the object as a whole to weigh less

Let’s simplify it further by considering Earth one of the hourglasses, with another one at the opposite end of our orbit, and letting the sun be the fulcrum.

Peak Warming Man said:

You can simplify this by considering two 1 tonne blocks of concrete instead of the sand.
Consider them inside a sliding frame, consider the concrete blocks and the sliding frame the hourglass.
Now place them on a beam supported by a fulcrum equal distance from the fulcrum.
Now elevate one of the blocks inside the frame. The system is still balanced, now release the raised block.

I’ll run that through Inventor Simulation when I get some time.

Well you have imparted energy to the hour glass by rotating it. That energy has to go somewhere.

jjjust moi said:

Peak Warming Man said:

You can simplify this by considering two 1 tonne blocks of concrete instead of the sand.
Consider them inside a sliding frame, consider the concrete blocks and the sliding frame the hourglass.
Now place them on a beam supported by a fulcrum equal distance from the fulcrum.
Now elevate one of the blocks inside the frame. The system is still balanced, now release the raised block.

I’ll run that through Inventor Simulation when I get some time.

Well you have imparted energy to the hour glass by rotating it. That energy has to go somewhere.

Julius Sumner Miller

I remember watching him when I was a kid

SCIENCE said:

dv is correct, elevating more of the mass causes the object as a whole to weigh less

I see no dvs here.

But anyway, whilst correct, this effect would be near 1/infinite, compared with the effect of the particles in free fall and the impact loads when they hit the sand on the bottom.

The Rev Dodgson said:

SCIENCE said:

dv is correct, elevating more of the mass causes the object as a whole to weigh less

I see no dvs here.

All SCIENCE, is Wrong.

OCDC said:

The Rev Dodgson said:

SCIENCE said:

dv is correct, elevating more of the mass causes the object as a whole to weigh less

I see no dvs here.

All SCIENCE, is Wrong.

So does that mean that God is right after all?

bob(from black rock) said:

OCDC said:

The Rev Dodgson said:

I see no dvs here.

All SCIENCE, is Wrong.

So does that mean that God is right after all?

How do you know there is a god?

see him/her

say Hi

talk about evolution?

Peak Warming Man said:

The inverted one would seem to weigh more because of the added inertia of the falling sand producing a down force on the balance beam on that side in addition to it’s weight.

This is the correct answer. The inverted hourglass ‘weighs’ more.

As a 7 or 8 year old I went with the sand in freefall wouldn’t be adding its weight and therefore the inverted hourglass would rise. Gee I was pissed off :)

> I can still vividly remember one episode of JSM’s show that had me enthralled and perhaps even kicked off my interest in science.

Ditto. One experiment I still remember vividly is lighting two candles oriented horizontally on opposite ends of a balance beam. The balance oscillated in simple periodic motion as first one and then the other candle burnt faster. For many years I wanted to calculate the oscillation period, but never did.