FORMULA SHELF 2 of 370

The arithmetic behind the work: what to measure, what to type in, and what the answer comes out as. Every formula says what the symbols mean and gives a worked example, so you can check it against a job you have already done.

Quick calculators. A calculator appears where the formula is a single, clean equation with clear symbols. It is a convenience, not an authority: double-check every result yourself, especially doses, loads, torque and safety-critical settings.

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Agronomy 1 formulas

Nitrogen to sulphur ratio in fertiliser

for oilseed rape and cereals, aim for about 6 kg N for every 1 kg S

SYMBOLS · most soils will release about 1 kg of sulphur for every 10 kg of nitrogen taken up by the crop

UNITS · kg/ha

HOW TO USE

Oilseed rape and grass are hungry for sulphur. Too little sulphur and the crop cannot use the nitrogen you have paid for, so the response to extra N is poor.

EXAMPLE

For 90 kg N/ha, apply 15 kg S/ha as ammonium sulphate.

sulphur nitrogen oilseed rape fertiliser

Geometry 1 formulas

Similar triangles

a / b = c / d

SYMBOLS · Corresponding sides of two similar triangles

UNITS · ratio

HOW TO USE

Scaling a drawing, finding an inaccessible height from a shadow, and setting out a roof.

EXAMPLE

A 2 m shadow from a 1.5 m post means a 12 m shadow is a 9 m tree.

triangle scale shadow

SOURCES & PROVENANCE 1 listed

This page is an AI-organised index. The label means the grouping and cross-links were compiled with AI; the information itself comes from the public-domain books, reports and manuals listed below. Open any source to read the local copy or follow the link to the original publication.

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The index is AI-organised; the linked sources are not.

Formulas collected and indexed with AI. The calculators are convenience tools; double-check every result before using it.