AQA · GCSE · Physics

    Course version: 8463 · Version from Sept 2016

    Weight is measured using a calibrated spring-balance (a newtonmeter).

    Full specification wording

    Gravity: Weight is measured using a calibrated spring-balance (a newtonmeter).

    Weight is a force, so it is measured with a calibrated spring-balance, also called a newtonmeter, which reads directly in newtons.

    Checked against the AQA 8463 specification (opens in a new tab) on .

    • Point 5 of 5
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Weight is a force, so it is measured with a calibrated spring-balance, also called a newtonmeter, which reads directly in newtons. Inside, a spring extends when the object is hung from it. Because the extension is directly proportional to the force applied, the scale is linear with evenly spaced divisions, which makes the instrument straightforward to calibrate. The spring must deform elastically so that it returns to its original length once the object is removed; if it is overloaded so far that it deforms inelastically it stays stretched and the readings are wrong afterwards; past the limit of proportionality the scale also stops being evenly spaced. To use it well, zero it first, hang it vertically, let the object come to rest and read the scale at eye level.

    What earns the marks

    • Naming the instrument as a calibrated spring-balance or newtonmeter, reading in newtons.
    • The extension of the spring being directly proportional to the force, giving an evenly spaced scale.
    • The spring deforming elastically, so it returns to its original length when the force is removed.
    • A correct technique, such as zeroing the instrument and reading the scale at eye level with the object stationary.

    Common mistakes and how to put them right

    • Naming a top-pan balance, which measures mass in grams rather than weight in newtons.

    • Reading the scale while the object is still swinging.

    • Failing to zero the newtonmeter before hanging the object on it.

    • Recording the reading in kilograms.

    • Overloading the spring past its limit of proportionality and continuing to use the readings.

    Exam tips

    • If asked why a spring suits this job, give the elastic deformation and the linear scale as two separate points.
    • Say the instrument is 'calibrated' in newtons; that word is in the specification and signals you know it reads force.
    • Mention eye level and a stationary object when a question asks how to improve accuracy.

    Try the lesson

    The start of the Gravity: Weight is measured using a calibrated spring-balance (a newtonmeter). lesson, made from checked teaching notes for this specification point.

    Have a go first

    What is the name of the instrument used to measure the weight of an object?

    Listen

    Weight is a force, so it is measured with a calibrated spring-balance, also called a newtonmeter, which reads directly in newtons. Inside, a spring extends when the object is hung from it. Because the extension is directly proportional to the force applied, the scale is linear with evenly spaced divisions, which makes the instrument straightforward to calibrate. The spring must deform elastically so that it returns to its original length once the object is removed; if it is overloaded so far that it deforms inelastically it stays stretched and the readings are wrong afterwards; past the limit of proportionality the scale also stops being evenly spaced. To use it well, zero it first, hang it vertically, let the object come to rest and read the scale at eye level. A strong answer earns marks for these points. naming the instrument as a calibrated spring-balance or newtonmeter, reading in newtons. the extension of the spring being directly proportional to the force, giving an evenly spaced scale. the spring deforming elastically, so it returns to its original length when the force is removed. a correct technique, such as zeroing the instrument and reading the scale at eye level with the object stationary. Exam tip: If asked why a spring suits this job, give the elastic deformation and the linear scale as two separate points.

    See it

    A top-down flowchart. The top node is 'Calibrated spring-balance (newtonmeter)'. From it, one branch leads to 'Reads in newtons'. A second branch leads to 'Spring extends when object is hung', which splits into 'Extension directly proportional to force' leading to 'Evenly spaced scale', and into 'Spring deforms elastically' leading to 'Returns to original length when force removed'. A third branch from the top node leads to 'Correct technique', which splits into four nodes: 'Zero it first', 'Hang vertically', 'Object at rest' and 'Read scale at eye level'.
    It shows the calibrated spring-balance reading in newtons, the two spring properties that make it suitable, and the steps for taking an accurate reading.

    Key words

    Say what each word means before you turn the card.

    newtonmeter

    Try answering aloud or in your head before turning the card.

    elastic deformation

    Try answering aloud or in your head before turning the card.

    linear scale

    Try answering aloud or in your head before turning the card.

    measurement technique

    Try answering aloud or in your head before turning the card.

    See every definition
    newtonmeter
    A calibrated spring-balance that is used to measure weight and reads directly in newtons.
    elastic deformation
    The spring deforms elastically so that it returns to its original length once the object is removed.
    linear scale
    Because the extension is directly proportional to the force applied, the scale has evenly spaced divisions.
    measurement technique
    Zero the instrument first, hang it vertically, let the object come to rest and read the scale at eye level.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. The top node is 'Calibrated spring-balance (newtonmeter)'. From it, one branch leads to 'Reads in newtons'. A second branch leads to 'Spring extends when object is hung', which splits into 'Extension directly proportional to force' leading to 'Evenly spaced scale', and into 'Spring deforms elastically' leading to 'Returns to original length when force removed'. A third branch from the top node leads to 'Correct technique', which splits into four nodes: 'Zero it first', 'Hang vertically', 'Object at rest' and 'Read scale at eye level'.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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