Scratch

here, i made a fairly simple representation of a clock, but it cant sense the current time(scratch cant do that) so it starts at exactly noon.
look at it on my profile.

Here's a slightly different approach.  I wanted the hands to move fairly continuously between the clock markings so all the hands move once per second.

http://scratch.mit.edu/projects/Paddle2SeeFixIt/110896

The code is very straightforward.  It does use a message to carry the timing pulse to all the hands but it doesn't use the sensor block or use any variables or counting.  There are also some scripts to allow setting of the hands but they could be omitted.

More advanced students could turn it into a chiming clock or an alarm clock.  Really advanced students could add in phases of the moon or add in a tide level hand.

Last edited by Paddle2See (2008-03-01 20:36:23)

One of the first clock simulations in scratch was by Graham:
http://scratch.mit.edu/projects/Graham/7266
Nine months ago now.

@Paddle2See

Very nice - I used the a similar approach myself but not quite as elegant (or as simple in fact    )

More advanced students could turn it into a chiming clock or an alarm clock.

Brilliant idea!!!

regards
Simon

kevin_karplus wrote:

One of the first clock simulations in scratch was by Graham:
http://scratch.mit.edu/projects/Graham/7266
Nine months ago now.

This version is very simple...it uses the timer instead of a timing pulse. 

There is an error in the constant being used to set the hour hand, however.  The constant inthe program is currently 0.0016667 when it should be 0.008333.  I know because I made the same mistake when I did my clock.  You think the rate for the hour hand should be 1/60 the rate of the minute hand (60 minutes per hour) but really it's 1/12 the rate of the minute hand (12 rotations of minute hand = 1 rotation of hour hand).

BTW - here is my original effort.
http://scratch.mit.edu/projects/SimpleScratch/111185


regards

Simon

I'm just going to write this down as I'm thinking

We all seem to be agreed that for every rotation of the secondhand - the minute had should move 1/60th of...


Right - I've worked out at this point where we are deviating from each other.

I agree, In a discrete moving clock, where the minute hand moves on every discrete minute, the hour hand has to move on 1/12th of a rotation every time the minute hand completes a full rotation.

But the same is not true in a pure analogue clock (well the second hand isn't pure in our simulations - but ignorning that discrepancy  ,  all hands are moving every single second so the hour hand does move at a rate of 1/60th of the minute hand.

Does this seem like a workable grand unified theory to you? 

regards

Simon

SimpleScratch wrote:

I

But the same is not true in a pure analogue clock (well the second hand isn't pure in our simulations - but ignorning that discrepancy  ,  all hands are moving every single second so the hour hand does move at a rate of 1/60th of the minute hand.

The hour hand needs to cover 1 hour in the time it takes for the minute hand to cover 60 minutes.    Hence your figure of 1/60.

BUT!

The difficulty lies in the fact that not only do the hands move at different speeds, but the distance travelled means different things depending on the hand.

1 rotation of minute hand = 60 mins
1 rotation of hour hand = 12 hours (not 60!)

One full rotation of the clockface of the minute hand is one hour.

1/60th of a rotation of the clock face by the hour hand is NOT an hour, it is 12 minutes.  To cover an hour on the clock face, the hour hand must move 5/60ths of a rotation, (1/12th of a rotation).

Hence Paddle's point that the angle moved by the hour hand needs to be 1/12 of the angle moved by the minute hand, NOT 1/60th

ok, i just made a digital version that is pretty simple if you want to check it out
the only real time it took was importing all the #s

Heh - because it is set to "only face left and right" instead of "can rotate"

The problem is that Sprite1 has the left-right arrow clicked, so it is not allowed to rotate.

MrSleeman wrote:

Hello everyone.
Here is my 1st attempt.
http://scratch.mit.edu/projects/MrSleeman/128923
I went for the 3 variables (H, M and S) method.
The second hand moves every pulse, the minute and hour hands only every minute

On my computer you can drag the hands around to set the time (full screen mode) but this does not work when I run it online.  Does anyone know why?

Yes, the problem is that the "On Clicked" event acts differently between the Scratch and the the Online environments.  In Scratch, "On Clicked" triggers on Mouse Down but online, "On Clicked" is triggered on Mouse Up.  If you switch to a Forever If loop, it should work in both places.