Foundations Of Physics Flashcards
What is the unit for mass?
Kilogram (kg)
What is the unit for length?
Metre (m)
What is the unit for time?
Seconds (s)
What is the unit for temperature?
Kelvin (K)
What is the unit for electrical current?
Amperes (A)
What is the unit for amount of substance?
Mole (mol)
What is the prefix and factor for tera?
T (10^12)
What is the prefix and factor for giga?
G (10^9)
What is the prefix and factor for mega?
M (10^6)
What is the prefix and factor for kilo
K (10^3)
What is the prefix and factor for deci?
d (10^-1)
What is the prefix and factor for centi?
C (10^-2)
What is the prefix and factor for mili?
m (10^-3)
What is the prefix and factor for micro?
μ (10^-6)
What is the prefix and factor for nano?
n (10^-9)
What is the prefix and factor for pico?
p (10^-12)
How do we convert from prefix to no prefix?
Multiply
How do we convert no prefix into prefix?
Divide
What is a homogenous equation?
The units on the left are the same as the units on the right
Making estimates?
Making a reasonable assumption for a physical quantity and then using this in a calculation
What is precision?
How close the results are to each other
What is accuracy?
How close you are to the real value
What is random error and how do we reduce it?
A random error are unpredictable as a result uncontrollable factors such as environmental conditions
This affects the precision of the measurement which affects the gradient of a graph
To reduce random error: repeat measurements several times and calculate an average from them.
What is systematic error and how do we reduce it?
Use of faulty instruments or from flaws in the experimental method
Repeated every time the instrument or method is used, which affects the accuracy of all readings obtained
To reduce systematic errors: instruments should be recalibrated or the technique being used should be corrected or adjusted
What is zero error?
Type of systematic error which occurs when an instrument gives a reading when the true reading is zero
E.g. scale that starts at 2g instead of zero
How do we find the uncertainty in a reading?
+/- half the smaller division
How do we find the uncertainty in a measurement?
At least +/- 1 smallest division
How do we find the uncertainty in repeated data?
Range/2
How do we find the Uncertainty in digital readings?
+/- the last significant digit unless otherwise quoted
How do we find the uncertainty in the natural log?
Absolute uncertainty in ln (x) = uncertainty in x over x
How do we calculate percentage uncertainty?
Uncertainty/ value
How do we combine uncertainties when adding and subtracting
Add the absolute uncertainties
How do we combine uncertainties when multiplying / dividing data?
Add the percentage uncertainties
How do we calculate uncertainty when raising to a power?
Multiply the percentage uncertainty by the power
How do we calculate the percentage uncertainty in the gradient
(Best gradient - worst gradient / best gradient) x 100
How do we calculate percentage difference?
(Experimental value - accepted value / accepted value) x100
What is a scalar?
Quantity which has only magnitude
What is a vector?
Quantity which has both magnitude and direction
List of vectors?
Displacement
velocity
acceleration
Force
Momentum
List of scalars
Distance
Speed
Mass
Time
Energy
Volume
Density
Pressure
Electric charge
Temperature
How do we combine vectors?
1) Add two vectors (as arrows)
2) link the vectors head to tail
3) form the resultant vector from linking the tail of one to the head of the other
4) calculate the resultant using Pythagoras theorem
How do we calculate the direction?
Found from the angle it makes with the horizontal or vertical
Calculating the angle can be done using trigonometry
How do we calculate vectors using scale drawings?
1) create a scale (e.g. 1cm = 1m)
2) put the vectors head to tail and draw them to the length of the scale
3) draw the resultant vector using a ruler
4) measure the angle of a resultant vector from the north bearing using a protractor
How do we combine vectors with coplanar forces?
1) identify the direction of all the forces
2) arrange these into a vector triangle keeping the same magnitude and directions
3) ensure the direction of the vectors form a close path
How do we resolve a single vector?
Break it down into its horizontal and vertical components
What is the equation for the horizontal component?
F(x) = F cos θ
What is the equation for the vertical component?
F (y) = F sin θ
How do we calculate a force perpendicular to the slope?
mg cos θ
How do we calculate the force parallel to the slope?
mg sin θ
Exam tip for resolving vectors?
Horizontal component is always adjacent to the angle
