# TABULA/samples/Church Clock

This is SAMPLE1. To work with this sample, enter \$1

```Church Clock
┌ {1}       75 ft    height of tower
├ {2}      800 kg    mass of weight
├ {3}    9.813 m/s²  acceleration; gravity=
┌ └>{4}   179458 J     energy stored in hanging weight
│ ┌ {5}    3.100 A h   battery charge=
│ ├ {6}       17 V     battery potential=
├ └>{7}   189720 J     energy stored in battery
└>  {8}    0.946 /     {4}/{7}
```

## Rationale

The clock of a historic church is driven by a heavy weight which needs to be hauled daily up to the top of a 75 ft tower.

The volunteer for this task wonders how much energy is thereby stored, and how this compares with the energy stored in the battery of his laptop computer, which also contains a clock.

To his astonishment, the two energy quantities are roughly equal.

What mass of hanging weight would make them exactly equal?

## Try it out

1. Select item {1} and click tool hold
This holds {1} to stop its value changing at the next step.
2. Select item {8} and click tool set1u
This forces {4} to become equal to {7}
3. Note the increase in "mass of weight" {2}.
4. Reload the sample and repeat these steps. But this time hold item {2} to keep the weight fixed, not {1}.
5. Note the increase in "height of tower" {1}.

## Build this t-table

1. [UNFINISHED]