# Archimedes' wheel

ryukyu
I am going to be doing a demonstration of Archimedes' wheel for some 6-9 year-old students and would like to try to figure out the work done by the wheel to lift 10 liters of water 1m vs the lifting of a 10 liter pale the same height.

Anyone know of a way to easily figure the work done in turning the screw if I were to fill the screw completely and turn it?

I am an electrical engineering guy so this is outside my comfort zone, but would appreciate anyone who is willing to work through it with me.

Gordianus
Neglecting friction forces the work is the same because every turn raises the same amount of water the same distance.
What Archimede's screw acomplishes is a reduction of applied force.
If you have a long handle, every time you turn it 360 degrees, your hand travels a long distance. Thus, the required force is smaller.
The same happened with old-fashioned car jacks. A long handle turned a fine-pitched screw

Homework Helper
Another big advantage is that it can't spill any water, unlike most other methods.

Are you seriously going to teach 6-9 year olds about work and energy?

Or is this an excuse for a field holiday working in your diamond mine?

(btw, it's Archimedes' screw … a google image search for Archimedes' wheel shows an ordinary worm gear for lifting a bucket out of a well )

ryukyu
Thanks for the replies thus far.

@tiny-tim: No I am not aiming to teach them about work and energy, but I do like to back my demonstrations with math when I make claims like "this takes less work than this.." especially when parents start asking questions.

@Godianus: I'm not making the connection. It seems like it would take less work (since there is less applied force). I guess I should make the experiment to state 1m up and 1m right, indicating the use of an inclined plane as well.

So, neglecting friction, this is not less work than lifting a bucket 1m and moving it right 1m?

Alvasin
The word propeller conjures images of helicopters, beanie hats, and toy boats. However, in the early 1800s propellers generally meant paddle-wheels. That began to change with the launch of the Archimedes in May of 1839. The ship was unique in an age of paddle-wheel steamers. The Archimedes was steam powered, but was not propelled by paddle-wheels. Instead, she was fitted with a device described to the patent office as "an improved propeller" in the shape of "a sort of screw, or worm." The Archimedes was only the first in a series of practical screw-propelled ships.

Gordianus
Thanks for the replies thus far.

@tiny-tim: No I am not aiming to teach them about work and energy, but I do like to back my demonstrations with math when I make claims like "this takes less work than this.." especially when parents start asking questions.

@Godianus: I'm not making the connection. It seems like it would take less work (since there is less applied force). I guess I should make the experiment to state 1m up and 1m right, indicating the use of an inclined plane as well.

So, neglecting friction, this is not less work than lifting a bucket 1m and moving it right 1m?

Yes, Archimedes' screw doesn't reduce the amount of work, we apply less force but our hand travels a longer distance.

Thanks for the replies thus far.

@tiny-tim: No I am not aiming to teach them about work and energy, but I do like to back my demonstrations with math when I make claims like "this takes less work than this.." especially when parents start asking questions.

@Godianus: I'm not making the connection. It seems like it would take less work (since there is less applied force). I guess I should make the experiment to state 1m up and 1m right, indicating the use of an inclined plane as well.

So, neglecting friction, this is not less work than lifting a bucket 1m and moving it right 1m?

Correct. It requires less force, but that force is applied over a significantly larger distance. Neglecting friction (and the mass of the bucket), the work should be the same.