7TH GRADE · PHYSICS AND MEASUREMENTS
Measuring instruments and accuracy
SI units, scales, division values, direct and indirect measurements.
The entire theory of the lesson is collected here; you can read it without an account. In interactive mode, the same theory appears as cards, followed by questions. with checking the answer and task, and progress is saved.
Basic Concepts
PHYSICAL QUANTITY
A measurable property of a body or phenomenon that is expressed by a number and a chosen unit.
Length, time, mass and temperature allow objects to be compared quantitatively, and the SI system makes the results understandable to everyone.
Scale and division price
The scale represents a series of instrument marks, and the division value is equal to the change in value between adjacent marks.
To read the device, two signed marks are found, their difference is divided by the number of intervals and then a reading is taken.
Accuracy and error
The error shows the possible deviation of the result from the value that best describes the measured quantity.
Direct measurement is obtained by the device, indirect measurement is calculated; Small identical bodies are placed in a row, the total length is measured and divided by the number of bodies.
Physical quantities
Length
The length of the body or the distance between selected points.
Unit: meter ·
Division price
The change in the measured value between adjacent scale lines.
Unit: meter ·
Length error
Assessment of possible deviation of the length measurement result.
Unit: meter ·
Lesson formulas
Scale division price
The difference between two signed values is divided by the number of spaces between them.
Tasks on the topic
Statements, answer options and the walkthrough.