L.2 Flashcards
What is the MKS system of units?
- metre
- kilogram
- second
What is the ampere unit for?
- electrical current
What is the kelvin unit for?
- temperature
What is the mole unit for?
- substance quantity
What is the candela unit for?
- luminous intensity
What are the fundamental quantities that make up dimensions?
- length (L)
- time (T)
- mass (M)
- temperature (0)
- charge (Q)
Are dimensions different from units? Why?
- yes.
- the same dimension can be expressed in different units for example 150 m and 2 miles bc they both have the same dimension of length. But we cannot add 3 m and 10 seconds because they have different dimensions
How can we use dimensions to aid understanding?
- we can use it to check simple formula or mathematical expressions to see if they are dimensionally correct
- if both the right and left hand side have the same dimensions , we did everything right
What is an exponent?
- the number of 0’s.
- 10 = 10^1 , 100 = 10^2 , 1000 = 10^3
For instance: light is 300,000,000 m/s
So the scientific notation of that would be: 3 x 10^8 m/s
How would 0.001 and 0.00024 be expressed in scientific notation?
- 0.001 = 10^-3
- 0.00024 = 2.4 x 10^-4
What happens when scientific notations are multiplied?
- the exponents are added together
- example: 10^4 • 10^2 = 10^(4+2) = 10^6
Or
(2 x 10^3) • (6 x 10^5)
= (2 x 6) • (10^3+5)
= 12 • 10^8
= 1.2 • 10^9
What happens to the exponents of scientific notation if they are divided?
- exponents are subtracted from each other.
- example:
10^5/10^2 = 10^5-2 = 10^3
Or
(9 x 10^5) / (3 x 10^7)
= (9/3) • 10^5-7
= 3 • 10^-2
What is the prefix and symbol of 10^12
Prefix: Tera
Symbol: T
What is the prefix and symbol of 10^9
Prefix: giga
Symbol: G
What is the prefix and symbol of 10^6
Prefix: mega
Symbol: M
What is the prefix and symbol of 10^3
Prefix: kilo
Symbol: k
What is the prefix and symbol of 10^-3
Prefix: milli
Symbol: m
What is the prefix and symbol of 10^-6
Prefix: micro
Symbol: u
What is the prefix and symbol of 10^-9
Prefix: nano
Symbol: n
What is the prefix and symbol of 10^-12
Prefix: pico
Symbol: P
What is the difference between vectors and scalar quantities?
Vector: has both magnitude and direction
Scalar: has only magnitude
What quantities do vectors have?
- position/displacements
- velocity
- acceleration
- force
What quantities do scalars have?
- time
- mass
- speed
- temperature
How can vectors be represented?
- graphically as arrows with a length proportional to its magnitude and orientated to indicate its direction
What are broken down components of vectors?
Ax and Ay are the components of Vector ‘A’ in the x and y direction respectively and can be obtained using the following expressions:
Ax = Acos0
Ay = Asin0
Calculate the components of vectors
Vector A has Ax and Ay
Ax (for the x direction on the graph):
Ax= Acos0
Ay (for the y direction on the graph):
Ay= Asin0
The raised knee - where does it hurt?
The force required to lift the knees results from the vector sun of the forces labelled 1,2, and 3 (1 at the knee and 2 and 3 at the back near butt)
The forces labeled 2 and 3 are produced by the muscle group in the lower back which is why it hurts there
Shoulders back and chest out - where does it hurt?
The resultant force required (which movies the shoulder back) is the vector sun of all the forces produced by the muscle group behind the shoulder. Which is why it hurts there not at the chest
Extended arm - where does it hurt?
- deltoid muscle.
- this is bc the angle between the deltoid muscle and the axis of the extended arm is so small(~18 degrees), the force produced by the deltoid muscle must be huge so that it’s vertical component is large enough to hold the arm extended. That’s why it hurts
Differentiate between accuracy and precision?
Accuracy - how close a measurement is to the true or accepted value
Precision - how close measurements of the same item are to each other
Identify different types of error in simple measurements.
- random errors
- systematic errors
- mistakes
Common measurements used by docs?
- weight
- temperature
- pulse
- blood pressure
- volume (hypodermic syringe etc)
