chapter 2: measurement and problem solving. practice measuring according to significant figures
TRANSCRIPT
Section 3: MeasurementChapter 2: Measurement and Problem Solving
Learning ObjectivesPractice measuring according to significant figures.
Measurement What is the volume of
water in the graduated cylinder in mL?
How many sigfigs is this? How many L is this? Express this number in
sci. notation.
Measurement Always take the measurement to one decimal
place past the smallest gradation (tic mark) Graduated cylinders
▪ Beakers/flasks/bottles /etc. are NOT used for measuring! Measure the volume of liquids ONLY with a graduated cylinder
Rulers
When using the electronic balance, record the entire number on the screen
21.75 mL
2.65 cm
3.53 cm
Measurement The bathroom
scale has markings at every 1 lb. Report the reading to the correct number of digits.
MeasurementThe unit system for
science measurements, based on the metric system, is called the International System of Units or SI units.
MeasurementThe standard of length
The definition of a meter, established by international agreement in 1983, is the distance that light travels in vacuum in 1/299,792,458 s. (The speed of light is 299,792,458 m/s.)
MeasurementThe standard of mass
The kilogram is defined as the mass of a block of metal kept at the International Bureau of Weights and Measures at Sèvres, France. A duplicate is kept at the National Institute of Standards and Technology near Washington, D.C.
MeasurementThe kilogram is a measure of mass, which
is different from weight. The mass of an object is a measure of the
quantity of matter within it.
The weight of an object is a measure of the gravitational pull on that matter.
Consequently, weight depends on gravity while mass does not.
Measurement
The standard of time The second is defined, using an atomic clock, as the duration of 9,192,631,770 periods of the radiation emitted from a certain transition in a cesium-133 atom.
