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Weigh lock

Weigh lock is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Weigh lock rather than just read about it. In short: A weigh lock is a specialized canal lock designed to determine the weight of barges in order to assess toll payments based upon the weight and value of the cargo carried. This requires that the unladen weight of the barge be known.

Weigh lock — main illustration
Weigh lock — illustration

Key takeaways

  • Weigh lock belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Weigh lock to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Weigh lock from memory before moving on to harder problems.

Reference excerpt

A weigh lock is a specialized canal lock designed to determine the weight of barges in order to assess toll payments based upon the weight and value of the cargo carried. This requires that the unladen weight of the barge be known. A barge to be weighed was brought into a supporting cradle connected by levers to a weighing mechanism. The water was then drained and the scale balance adjusted to determine the barge gross weight. Subtracting the tare weight (the weight of the barge when empty) would give the cargo weight. Originally weighlocks measured the weight of the barge, initially by measuring the displacement of water from the lock by collecting the liquid in a separate measuring chamber after the barge had entered. This method also requires that the unladen weight of the barge be known.

See also Weigh bridge, a device for weighing trucks and railcars.

References

External links Erie Canal — The Weigh Lock

Illustrations

Weigh lock: A weigh lock on the Lehigh Canal around 1873
A weigh lock on the Lehigh Canal around 1873
Weigh lock: Weigh lock on the Erie Canal in Syracuse, New York, in 1903. Today this building is the Erie Canal Museum. The current canal now passes well behind this location. The old route through the central city has long been filled in and is now a paved boulevard.
Weigh lock on the Erie Canal in Syracuse, New York, in 1903. Today this building is the Erie Canal Museum. The current canal now passes well behind this location. The old route through the central city has long been filled in and is now a paved boulevard.

Worked examples

Example 1 — a first encounter with Weigh lock

Start with the simplest possible case. Write down what Weigh lock claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Weigh lock before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Weigh lock ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Weigh lock

In research
Weigh lock appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Weigh lock in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Weigh lock is common in secondary-school and first-year university syllabi. It links to neighbouring topics Locks (water navigation), Weighing instruments, so understanding it makes those chapters shorter.
In everyday life
Look for Weigh lock outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Weigh lock in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Weigh lock means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Weigh lock out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Weigh lock in simple terms?

A weigh lock is a specialized canal lock designed to determine the weight of barges in order to assess toll payments based upon the weight and value of the cargo carried. This requires that the unladen weight of the barge be known.

Why does Weigh lock matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Weigh lock?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Weigh lock.

Tags

  • Locks (water navigation)
  • Weighing instruments

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