estimates and measurements
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Estimates and Measurements. Physical Science 2012. Which figure is longer?. Which orange circle is larger?. Which blue line is straighter?. What do you see?. A vase with flowers? Or the profile of two faces?. Physical magnitudes. A magnitude is a physical property that can be measured. - PowerPoint PPT PresentationTRANSCRIPT
"Trabajar en Ciencias 7", by Santillana.
Physical magnitudesA magnitude is a physical property that
can be measured.Examples are length, mass and
temperature.Is the taste of an ice cream a physical
magnitude?No, because it cannot be measured.A fundamental magnitude is independent
of any other magnitud: time, mass, length.A derived magnitude is based on two or
more other magnitudes: density, speed.
"Trabajar en Ciencias 7", by Santillana.
MeasurementsA measurement is the comparison of a
physical magnitude with a fix quantity.The result of a measurement is a
number and a unit.When you compare yourself to a meter,
you measure your height, which may be 1,5 m.
Some measurements are inexact, like a teaspoon of sugar in a recipe. Others are exact: a meter always measures the same.
"Trabajar en Ciencias 7", by Santillana.
EstimatesAn estimate is to assign a value to a
physical magnitude without using a measuring device/tool.
It is based on perception and the experience of who is making the estimate.
If you feel bad you may estimate that you have a fever, but your mother might estimate that your temperature is normal.
Instead of estimating, you can actually measure it with a thermometer.
"Trabajar en Ciencias 7", by Santillana.
PracticeExplain what is the difference
between a fundamental physical quantity and a derived physical quantity.
Underline the characteristic that is a physical magnitude: color, beauty, speed, taste, volume, temperature.
Explain why the following information is a measurement: length of a table is 78 cm
"Trabajar en Ciencias 7", by Santillana.
Practice – Estimates and MeasurementsMeasure the height of your
notebook with an inexact method, like assuming each finger is 1 cm. Then use a ruler.
Procedure: Estimate the time it takes to perform each task, and then measure it with an appropriate device:
Action Estimated time
Measured time
To sing “happy birthday”
To walk around the classroom