Topic 1 - Working As A Physicist (All Papers)

Question 1

List the seven base quantities

Answer 1

Mass
Length
Time
Current
Temperature
Amount of Substance
Luminous intensity

Question 2

List the seven base units

Answer 2

Kilogram (kg)
Metre (m)
Second (s)
Ampere (A)
Kelvin (K)
Mole (mol)
Candela (cd)

Question 3

What are the SI units of Force?

Answer 3

• Force = Mass x Acceleration
• Force = kg x ms^-2
• Force = kgms^-2

Question 4

List every prefix along with their symbol and multiplier

Answer 4

• Peta P x10^15
• Tera T x10^12
• Giga G x10^9
• Mega M x10^6
• Kilo k x10^3
• Centi c x10^-2
• Milli m x10^-3
• Micro u x10^-6
• Nano n x10^-9
• Pico p x10^-12
• Femto f x10^-15

Question 5

Convert 60nm to m

Answer 5

• 60 x 10^-9
• = 6 x 10^-8 m
• = 0.00000006m

Question 6

Convert 87MJ to J

Answer 6

• 87 x 10^6 J
• = 87,000,000 J

Question 7

Convert 6pF to F

Answer 7

• 6 x 10^-12 F

Question 8

Convert 9 gigaohms to ohms

Answer 8

• 9 x 10^9 Ohms

Question 9

Convert 10um to m

Answer 9

• 10 x 10^-6 m
• = 1 x 10^-5 m

Question 10

Define resolution:

Answer 10

• The smallest measuring interval and the source of uncertainty in a single reading.

Question 11

Define uncertainty:

Answer 11

• The the interval within which the true value can be considered to lie with a given level of confidence or probability.

Question 12

Define systematic error.

Answer 12

• A systematic error is a fault with the equipment.
• These errors are usually in one direction (e.g results all too low/high) and can be compensated for.

Question 13

Define human error.

Answer 13

• A random error is usually due to human error in taking the readings.
• These are always given as plus or minus uncertainties.
• They affect precision.

Question 14

Define error.

Answer 14

• The difference between the measurement result and the true value if a true value
  is thought to exist.
• This is not a mistake in the measurement. The error can be due to both systematic and random effects and an error of unknown size is a source of uncertainty.

Question 15

How to estimate absolute uncertainty:

Answer 15

• Half the resolution of the instrument
  OR if the readings are repeated:
• half the range of the repeats and a mean calculated for the main reading.

Question 16

How to calculate percentage uncertainty:

Answer 16

(Absolute Uncertainty / Actual Reading) x 100

Question 17

Define accurate.

Answer 17

• A measurement result is considered accurate if it is judged to be close to the true value.

Question 18

Define precise.

Answer 18

• A quality describing the closeness of agreement (consistency) between values obtained by repeated measurement.

Question 19

Compounding Uncertainties 1:

When the measured quantities are multiplied or divided, _____________________

Answer 19

• The percentage uncertainties are added!

Question 20

Compounding Uncertainties 2:

If the quantities are squared or cubed in the calculation, ___________________

Answer 20

• You multiply the uncertainty by the power!

Question 21

Steps on how to use vernier scales:

Answer 21

• STEP 1: Where does the first line on the bottom scale roughly line up with on the top one?
• STEP 2: Where does a second line on the bottom scale EXACTLY line up with one on the top one?
• STEP 3: The first reading represents 0.x mm and the second reading represents 0.0x mm. Add these together.

Question 22

Steps on how to use Micrometers:

Answer 22

• STEP 1: Where does the EDGE of the vertical scale approximately line up with the horizontal?
• STEP 2: Has it passed the half way mark?
• STEP 3: Then add the reading from the side scale onto it.

Question 23

Compounding Uncertainties 3:
If adding or subtracting data, _____________

Answer 23

• Add absolute uncertainties

Question 24

To reduce random errors (3 ways):

Answer 24

• Take at least 3 repeats and calculate a mean, allowing anomalies to be identified.
• Use computers/data loggers/cameras to reduce human error and enable smaller intervals.
• Use appropriate equipment e.g a micrometer has a higher resolution than a ruler.

Question 25

To reduce systematic errors (3 ways):

Answer 25

- Calibrate apparatus by measuring a known value e.g 1kg on mass balance. - Correct for background radiation by measuring it beforehand and excluding it from final results. - Read the meniscus at eye level to reduce parallax error and use controls on experiments.

Question 26

Define meniscus:

Answer 26

- Central curve on the surface of a liquid.

Question 27

What is an application of science?

Answer 27

- A use of scientific knowledge in order to carry out a specific action.

Question 28

What is an implication of science?

Answer 28

- A direct or implied consequence of the knowledge of a particular concept.

Question 29

Different types of implications:

Answer 29

- Commercial (money) - Legal (law) - Ethical (morality) - Social (society)

Question 30

What is the role of the scientific community in validating new knowledge?

Answer 30

- Publish experimental evidence. - This is then peer-reviewed by the community. - The evidence can then become validated and eventually accepted.

Question 31

How does society use science to inform decision making in policy making?

Answer 31

- Ensure that government policies are beneficial to society

Question 32

How does society use science to inform decision making in the criminal justice system?

Answer 32

- Evidence is analysed scientifically in order to provide information about how a crime was carried out

Question 33

- How does society use science to inform decision making in everyday life?

Answer 33

- Scientific knowledge of a healthy lifestyle. - An example is walking to school instead of taking the bus.