Grandezas e Unidades

Summary

This lesson introduces the concept of physical quantities and units. It explains that physical quantities, like mass, length, and speed, are measured with devices such as rulers, scales, and speedometers. The lesson also covers the International System of Units (SI), detailing the standard units for different quantities, including meters for length and kilograms for mass. Additionally, the teacher distinguishes between scalar quantities (with only magnitude, such as mass and time) and vector quantities (which also have direction, like force and velocity), providing a foundation for understanding these key physical concepts.

Takeaways

• 😀 A physical quantity is anything measured by instruments, such as length, mass, or speed.
• 😀 A physical unit is the standardized quantity of a specific physical quantity.
• 😀 Examples of measuring instruments include a ruler (for length), a balance (for mass), and a speedometer (for speed).
• 😀 Length is measured in units like centimeters or meters, and mass in kilograms or grams.
• 😀 The speedometer measures speed, commonly in kilometers per hour (km/h).
• 😀 The International System of Units (SI) defines standardized units: meters for length, kilograms for mass, seconds for time, amperes for current, Kelvin for temperature, moles for substance amount, and candelas for luminous intensity.
• 😀 Physical quantities can be divided into two categories: scalar and vector.
• 😀 Scalar quantities have only magnitude and unit, such as mass, length, or temperature.
• 😀 Vector quantities have both magnitude, unit, direction, and sense, such as force, velocity, and acceleration.
• 😀 Understanding direction and sense in vector quantities is important, such as vertical or horizontal direction and upward or downward sense.

Q & A

What is the difference between 'grandeza' and 'unidade física' in the context of the lesson?

'Grandeza' refers to any measurable physical quantity, like mass, length, or speed. 'Unidade física' is the specific standard measurement used for a particular grandeza, such as kilograms for mass or meters for length.

What are some examples of devices used to measure grandezas?

The examples provided are a ruler (for measuring length), a balance (for measuring mass), and a velocimeter (for measuring speed).

What is the unit of measurement for length in the International System of Units (SI)?

The unit for length in the SI system is the meter, though other units like centimeters or kilometers can also be used, depending on the measurement scale.

What is the standard unit of mass in the SI system?

The standard unit of mass in the SI system is the kilogram (kg).

What is the unit for measuring speed as mentioned in the lesson?

The unit for speed, as per the lesson, is kilometers per hour (km/h).

What are the basic units of measurement in the International System of Units (SI)?

The basic units are: length (meter), mass (kilogram), time (second), electric current (ampere), thermodynamic temperature (Kelvin), amount of substance (mole), and luminous intensity (candela).

How can physical grandezas be classified?

Grandezas can be classified as scalar or vector. Scalar grandezas have only magnitude (e.g., mass, time), while vector grandezas have both magnitude and direction (e.g., force, velocity).

What is an example of a scalar grandeza and its unit?

An example of a scalar grandeza is mass, with the unit being kilogram (kg).

What defines a vector grandeza, and can you provide an example?

A vector grandeza is defined by both its magnitude and its direction. Examples include force, acceleration, and velocity. For instance, velocity is a vector because it also has direction (e.g., moving to the right or upward).

How is the direction and sense of a vector grandeza determined?

The direction of a vector grandeza can be either vertical or horizontal, while its sense can be indicated as moving up or down, left or right.