physics

Pinch (action)

Pinch (action) is a physics 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 Pinch (action) rather than just read about it. In short: A pinch is a grip of a flexible object in which a portion is taken between two fingers, until it hurts, or something of resemblance and squeezed so the gripped portion of the object is lifted from its normal level. By extension, that which is taken in the grip is referred to as a "pinch." When the fingers are used to perform a pinch, the action usually consists of the thumb and one other finger.

Key takeaways

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

Reference excerpt

A pinch is a grip of a flexible object in which a portion is taken between two fingers, until it hurts, or something of resemblance and squeezed so the gripped portion of the object is lifted from its normal level. By extension, that which is taken in the grip is referred to as a "pinch." When the fingers are used to perform a pinch, the action usually consists of the thumb and one other finger. The closer to the thumb the other finger is located, the stronger the pinch.

Pinch of the skin The term "pinch" often refers to the action being taken on the skin. A pinch of the skin displaces the skin and blood beneath from its natural position, and may inflict a minor degree of pain, which may increase if the amount of skin being pinched is smaller, but is usually tolerable to most. Pinching the skin can result in pinch marks, a cutaneous condition, and when on the ears or in the genital region of male children, may be suggestive of child abuse.

Medical uses Pinching has the following uses in health care and medicine:

The skin is often pinched prior to giving an injection in order to get the needle in the desired location. In neurology, pinching can be used to determine pain sensitivity for a certain area of skin. Can be used to determine resiliency in the skin of an aged person. When the skin is pinched, the amount of time the pinch remains visible following the pinch is an indicator. When skin has been damaged by the sun, pinching can be used to determine the amount of damage. Examining the appearance with varying amounts of time following the pinch can be used to determine the amount of damage. In determining dehydration, pinching the skin can serve as a test. The speed at which the pinch turns back can help determine the level of dehydration. The slower it goes back, the more severe the dehydration. Body fat percentage can be determined the skinfold test, in which a pinch of skin is precisely measured by calipers at several standardized points on the body to determine the subcutaneous fat layer thickness. These measurements are converted to an estimated body fat percentage by an equation. Pinching is used as part of the diagnosis of schleroderma. In schleroderma patients, the skin between the fingers becomes too difficult to pinch. In veterinary medicine, small amounts of animal skin is pinched in order to perform grafting.

References

Illustrations

Worked examples

Example 1 — a first encounter with Pinch (action)

Start with the simplest possible case. Write down what Pinch (action) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, 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 Pinch (action) 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 Pinch (action) 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 Pinch (action)

In research: Pinch (action) appears in physics 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 Pinch (action) 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: Pinch (action) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Pain infliction methods, Skin, Skin conditions resulting from physical factors, so understanding it makes those chapters shorter.
In everyday life: Look for Pinch (action) 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Pinch (action)” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Pinch (action) in 20 minutes

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

Frequently asked questions

What is Pinch (action) in simple terms?

Why does Pinch (action) matter?

Because it connects several physics 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 Pinch (action)?

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 Pinch (action).