Topic 3 Flashcards
What is mass?
The measure of the amount of matter in an object.
What is balance?
Common type of measuring tool for mass.
Most balances compare the pull of gravity on the object you want to weight to the pull of gravity on standard masses
What is a primary standard?
- A specific cylinder of metal used to measure mass,
in the metric system - Amount of material in the primary standard was 1
kilogram (kg) - Countries keep an exact copy of the primary
standard
How do we measure mass (units)?
Smaller masses are usually expressed
in grams (g). Larger are in kilograms. Kilo means thousand and milli means one millionth (really small).
How do we measure forces?
Newtons
What is a force meter?
■ Common lab equipment also known
as a spring scale
■ Not very accurate
■ Less expensive than electronic
sensors
■ When forces are very large it is hard
to measure them, it is often done with
calculations based on motion
What do you need to describe a force?
Its size and its direction
What is weight?
A force
between any two objects that
pull them together
How do we measure weight?
Newtons
What is gravitational force?
■ Attraction between two
objects
■ Is based on the masses of
the objects
■ Gravity is very small in
normal objects
■ Gravity is large in huge
objects (planets)
■ In everyday language we call
gravitational force weight
■ Instead of saying there is a
10N gravitational force
between a 1kg mass and the
Earth we say the object
weighs 10N.
Which changes and which always stays the same: mass and weight?
Mass stays the same (size). Weight changes (how much force is put on an object) based on gravity.
What is a force diagram?
Simple picture that shows the strength
and direction of one or more forces.
■ A circle or rectangle represents the
object
■ Each force is shown by an arrow.
– Length of the arrow shows the size of the
force
