SCIENCE
Mass, Weight, and Density
The density of a substance is the relationship between the mass of the substance and how
much space it takes up (volume).
● How light or heavy object the object is.
Density of water = 1g/cm³
Formula: D = mass/volume
Units= kg/m², kg/L
Mass is the quantity of matter that makes up an object. It can also be thought of as how much
an object resists a change in motion.
a. Mass remains constant
b. The basic Sl unit for mass is the kilogram (kg), but smaller masses may be measured
in grams (g).
c. Mass is different from weight, which changes with changes in gravity. Mass always
stays the same, while weight can change depending on the gravitational force.
d. The amount of gravity in earth is 9.8 per seconds²
Weight is the force acting on an object due to gravity. The weight of an object depends on the
gravitational field at the point in space where the object is.
● The SI unit for weight is the Newton (N).
● Kilogram per meter squared is Newton
● W = mg, where W is weight, m is mass, and g is the acceleration due to gravity.
● Formula: W = Mass x gravity
● The gravity is affected because of the size of an object.
Gravity should push us towards the center.
● Formula: G = weight x mass
● Units= kg mls²
Higher mass = sink in the water
Lower mass = lower density
Higher mass = higher density
Lower volume =higher density
Higher volume = lower volume
Temperature
● How hot/cold an object is
● What causes these particles to spread apart when it's in high temperature is kinetic
energy
● Proportional to the average translational kinetic energy of the atoms that make up
objects.
Celsius= (Anders Celsius) 1701-1744
Fahrenheit= (Gabriel Daniel Fahrenheit) 1686-1736
Kelvin= (William Thompson)
Conversion of units
4/5 difference of F° from C°
Kelvin (k) is a derived unit with an equivalent of kg/m³
● Temperature of an object should be in whole number (round down)
Formulas:
C= 5/9 (F° - 32)
F= 9/5 (C° + 32)
K= (C° + 273.15k)
Significant Figures
● Significant figures are the number of digits in a given value or a measurement,
necessary to decide the accuracy and precision of measurement.
Significant Figures Rules:
● All non-zero numbers ARE significant.
● Zeros between two non-zero digits ARE significant.
● Leading zeros are NOT significant.
● Trailing zeros to the right of the decimal ARE significant. ...
● Trailing zeros in a whole number with the decimal shown ARE significant.
How to calculate significant figures (factor label method)
- Write the given number as a fraction
- Multiply the given number by a fraction made up of equivalent conversions
- Arrange the conversion units in a fraction so that all units cancel except the desired unit
Tips
● Treat units similarly to numerical values
● Multiply by as many conversion factors as needed
● Cancel units by placing the same unit in the numerator and denominator of neighboring
conversion factors
● Numbers and units are considered separately
Scientific Notation
● Scientific notation is a way of expressing numbers that are too large or too small to be
conveniently written in decimal form, since to do so would require writing out an
inconveniently long string of digits.
● Standard scientific notation represents a number as a factor multiplied by a power of 10;
3,560,000 is expressed as 3.56 × 106.
