General

Question 1

Absolute Uncertainties

Answer 1

• The interval that a value is said to lie within, with a given level of confidence.
• (Range of measurements ÷ 2)
  Biggest - smallest

Question 2

Anomalies

Answer 2

• Data points that don’t fit the pattern of the data.
• You should determine why an anomalous result has occurred before removing it.
• Repeat readings help remove anomalies.

Question 3

Percentage Uncertainties

Answer 3

The uncertainty of a measurement, expressed as a
percentage of the recorded value.
𝑧 = 𝑥 ± 𝑦 𝛿𝑧 = 𝛿𝑥 + 𝛿𝑦

(gradient of line of best fit - gradient of line of worst fit) ÷ gradient of line of best fit

Question 4

Precision

Answer 4

• Precision is a measure of how close a measurement is to the mean value.
• It only gives an indication of the magnitude of random errors, not how close data is to the true value.

Question 5

Random Errors

Answer 5

• Random error is an unpredictable variation between measurements that leads to a spread of values about the true value.
• Random error can be reduced by taking repeat measurements.
• Examples include parallax errors.

Question 6

Repeatable

Answer 6

The same experimenter can repeat a measurement using the same
method and equipment and obtain the same value.

Question 7

Reproducible

Answer 7

the ability to achieve consistent results when an experiment is repeated by different experimenters using various methods or equipment.

Question 8

Resolution

Answer 8

The smallest change in a quantity that causes a visible change in the
reading that a measuring instrument records.

Question 9

Resolution of Forces

Answer 9

The splitting of a force into its horizontal and vertical
components.

Question 10

Scalar Quantities

Answer 10

A quantity that only has a magnitude, without an associated
direction. Examples include speed, distance and temperature.

Question 11

SI Units + prefixes

Answer 11

The standard units used in equations. They are: metres, kilograms, candela, seconds, amps, Kelvin and moles.
Tera (T)- 10^12
Giga (G)- 10^9
Mega (M)- 10^6
Kilo (k)- 10^3
Milli (m)- 10^-3
Micro (μ)- 10^-6
Nano (n)- 10^-9
Pico (p)- 10^-12
Femto (f)- 10^-15

Question 12

Systematic Errors

Answer 12

• Causes all readings to differ from the true value by a fixed amount.
• Systematic error cannot be corrected by repeat readings, instead a different technique or apparatus should be used.

Question 13

Triangle of Forces

Answer 13

• A method of finding the resultant force of two forces is called the triangle of forces.
• The two forces are joined tip to tail, and the resultant is the vector that completes the triangle.

Question 14

Vector Quantities

Answer 14

• A quantity that has both a magnitude and an associated direction.
• Examples include velocity, displacement and acceleration.

Question 15

Vernier Scales

Answer 15

• The type of scale used on calipers and micrometers is called a vernier scale.
• It involves reading from a fixed scale and a moving scale to produce accurate measurements.

Question 16

Zero Errors

Answer 16

• A form of systematic error, caused when a measuring instrument doesn’t read zero at a value of zero, is called a zero error.
• This results in all measurements being offset by a fixed amount.

Question 17

Significant figures

Answer 17

• Copy the s.f. of the raw data which has the least s.f. (or 3 s.f. to play it safe)
• Zeros that come before all non-zero digits are not significant

Question 18

How to answer 6 markers

Answer 18

• Break down the question
• identify independent and dependent variables
• Equipment + measurements
• accuracy and errors?
• safety/controls?
  -formulas
• y=mx+c for analysis

An example for accuracy, errors and safety

Systematic Errors:
- Residual magnetism from the electromagnet may cause time (t) to be recorded as longer than it should be.

Random Errors:
- Uncertainty in height (h) due to using a metre rule with 1 mm precision.
- Parallax error when reading h.
- Ball may not fall centrally through the light gates.
- Reduced by repeating the experiment 3-5 times for each h and calculating an average time (t).

Safety Considerations:
- Electromagnet requires current:
- Keep water away to avoid risks.
- Only switch on after setup to reduce electrocution risk.
- Use a cushion or soft surface to catch the ball-bearing and prevent damage.
- Secure the tall clamp stand with a G-clamp to ensure stability.

Question 19

If they Introduce a new equation

Answer 19

Work in units

Question 20

Coplanar forces

Answer 20

• Act in the same plane

Question 21

Electrostatic energy

Answer 21

Due to the separation between the molecules and their position within the structure

Question 22

Temperature

Answer 22

• Absolute zero is the lowest possible temperature, defined as 0 K or -273°C.
• At absolute zero, molecules have zero kinetic energy, and no further energy can be removed from the system.
• 𝑇(K) ≈ 𝜃(℃) + 273

Question 23

The Four Fundamental Forces of Nature

Answer 23

• Gravity: The weakest force, but acts over infinite distances. It’s responsible for the attraction between objects with mass.
• Electromagnetism: Governs the interaction between charged particles. It’s responsible for electricity, magnetism, and light
• Strong Nuclear Force: The strongest force, but acts over very short distances. It holds the nucleus of an atom together.
• Weak Nuclear Force: A short-range force involved in certain types of radioactive decay.

Question 24

Inertia

Answer 24

• Tendency for an object’s motion to stay constant if there’s no resultant force

Question 25

Squared Or Cubic Conversions

Answer 25

Cube or square the conversion factor too

• E.g. 1 mm³ = 1 / (1000)³ = 1 × 10^-9 m³
• E.g. 1 cm³ = 1 / (100)³ = 1 × 10^-6 m³

Question 26

Total pressure

Answer 26

Total Pressure:

• Total pressure = Hydrostatic pressure + Atmospheric pressure.
• Atmospheric pressure (barometric pressure) = 101,325 Pa.

Key Points:

• Pressure values can vary widely and use metric prefixes (e.g., kPa, MPa).
• Ensure all pressures are in the same units (e.g., convert everything to Pascals (Pa)) to avoid errors.