Scientific Method and Measurement Principles

The Scientific Method and Measurement

1. The Scientific Method

Scientific work describes the laws of nature through a valid and reliable process known as the scientific method.

1.2. Developing a Hypothesis

A scientific hypothesis is an assumption that must meet the following conditions:

• It must refer to a real situation.
• It must be stated as accurately as possible, using specific variables.
• The relationship between the hypothesis variables must be observable and measurable.

1.3 The Experiment

An experiment involves repeating the observation of a phenomenon under controlled conditions, sometimes replicating situations that do not occur naturally.

Variables in an Experiment

A variable is a factor whose change influences the results of an experiment.

A control is an element of the experiment that remains constant. Its purpose is to provide a basis for comparing the changes observed in the experiment.

1.5 Laws and Theories

Scientific laws are hypotheses confirmed by multiple experiences.

• Scientific theories are sets of laws whose primary function is to explain the regularities described by those laws.
• Theories are constructed to allow reliable predictions about phenomena not yet known when they were formulated.

The features of a scientific theory include:

• Listing numerous facts.
• Suggesting new relationships.
• Enabling predictions that can be experimentally verified.
• Being useful for solving quantitative problems.

2. Measurement

A magnitude is any measurable property of bodies.

There are seven basic or fundamental magnitudes: length, mass, time, temperature, electric current, luminous intensity, and amount of substance. All others are derived.

Measuring a magnitude involves comparing it with another of the same type, called a unit, to determine how many times it is contained within it.

2.2 Scientific Notation

Scientific notation expresses a number as a decimal number with a single non-zero digit before the decimal point, multiplied by a power of 10 with a positive or negative exponent.

3. Measuring Instruments

Measuring instruments are necessary because some quantities or variations of a magnitude are too small to be perceived by the senses.

3.1 Accuracy and Sensitivity

The accuracy of a measuring instrument refers to the smallest change in a magnitude that the instrument can detect or determine.

The sensitivity of a measuring instrument is its ability to discern small variations within the intervals of a magnitude.

A measuring instrument is more sensitive the lower the value of its accuracy, meaning the more precise it is.

3.2 Significant Figures and Rounding

Significant figures are the digits in a measurement that are known with certainty.

Rounding refers to the process of adjusting figures located to the right of the last significant figure.