Week 1 - Uncertainties in Scientific Measurements Flashcards
Fundamental Units, Matter In Motion, Uncertainty in Measurement
Define Measurement
Gives a property and number to something.
eg. 2 metres
What could be mistaken for ‘measurements’, but are not?
(3)
Comparisons (2 pieces of string)
Counting
Tests (normally lead to a yes/no answer or a pass/fail answer)
What are the 3 fundamental quantities; describe them and their significance
(3)
Length
Mass
Time
Significant as all other physical quantities can be constructed from these 3
What are all the fundamental units of measurement and their SI unit?
(8)
Length (m, metre)
Time (s, second)
Mass (kg, kilogram)
Current (A, ampere)
Temperature (oC, celcius)
Thermodynamic temperature (K, Kelvin)
Amount of substance (mol, mole)
Luminous intensity (cd, candela)
What are the quantities of motion; describe their significance.
(3)
Displacement
Velocity
Acceleration
Significant as these concepts can be used to study all objects in motion (provide the basis for)
Define Displacement; SI Unit and TYPE of quantity
Change in position; SI Unit is M, Metre.
Vector quantity - requires both magnitude and direction to fully describe it
2 factors
Define a vector quantity; provide example
A quantity that requires both magnitude and direction to completely describe it;
eg. displacement
1 factor
Define a scalar quantity; provide example
A quantity completely described by magnitude alone;
eg. time, weight
Define speed; what type of quantity is it and why?
Defined as total distance of an object / total time elapsed; scalar quantity - does not need direction to describe it
Define velocity; the formula, SI Unit; type of quantity and why?
The rate at which displacement occurs (the change in object’s position);
displacement/time;
m/s;
vector quantity - needs both direction and magnitude to describe it
Describe the difference between speed and velocity using an example of 2 cars that travel the same distance.
Car 1 - directly from point A to B
Car 2 - wavey motion from point A to B
Car 1 and 2 both have the same average velocity - as they have the same displacement in the same interval (change in displacement/change in time)
Speed of Car 2 is greater as it has travelled a GREATER distance than Car 1
Speed = total distance/total time
Describe the difference in displacement and distance; give an example
Displacement is the change in POSITION of an object (vector quantity); distance is length between objects/points that DOES NOT REGARD DIRECTION (scalar quantity)
eg. Throwing a ball up in air and catching it; distance is x metres, displacement is 0
be specific
Define acceleration; unit and quantity type
type of change
Change in velocity (non-uniform; meaning change in speed) over time; m/s^2; vector quantity
Acceleration interpretation: sign of velocity and acceleration are the SAME
V= inc.
a= uniform (unchanging)
speed will be increasing; displacement over time is increasing = VELOCITY
speeding up, foot on the gas
**
Acceleration interpretation: sign of velocity and acceleration are DIFFERENT
V = inc.
a = uniform (stays unchanging
speed is decreasing;
eg. displacement over time is decreasing = VELOCITY; acceleration is uniform (unchanging speed)
breaking, slowing down
