Scottish National 4 (Nat 4) Physics (National 4) Flashcards

24 sample cards from the Physics (National 4) deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What type of wave is sound, and can it travel through a vacuum?

   Sound is a longitudinal wave; it cannot travel through a vacuum because it needs a medium (particles) to travel through.

2. How are loudness and pitch of a sound related to the wave's amplitude and frequency?

   Loudness depends on amplitude (larger amplitude = louder); pitch depends on frequency (higher frequency = higher pitch).

3. What instrument is used to measure sound level, and what is the unit of sound level?

   A sound level meter; the unit is the decibel (dB).

4. Name the three types of nuclear radiation.

   Alpha ($\alpha$), beta ($\beta$) and gamma ($\gamma$) radiation.

5. Rank alpha, beta and gamma radiation in order of penetrating power, from least to most.

   Alpha (least, stopped by paper/skin) < beta (stopped by aluminium) < gamma (most penetrating, reduced by thick lead/concrete).

6. What is each type of nuclear radiation made of?

   Alpha: a helium nucleus (2 protons + 2 neutrons). Beta: a fast-moving electron. Gamma: high-energy electromagnetic radiation (a wave).

7. What is meant by an ionising radiation, and which type is most strongly ionising?

   Ionising radiation knocks electrons off atoms, creating charged ions; alpha radiation is the most strongly ionising.

8. State the average (mean) speed equation linking distance and time.

   $v = \dfrac{d}{t}$, where $v$ is speed (m/s), $d$ is distance (m) and $t$ is time (s).

9. Define acceleration and write its equation.

   Acceleration is the change in velocity per unit time: $a = \dfrac{v - u}{t}$, where $u$ is initial velocity and $v$ is final velocity, measured in $\text{m/s}^{2}$.

10. What is the difference between speed and velocity?

    Speed is how fast something moves (a scalar, magnitude only); velocity is speed in a stated direction (a vector, magnitude and direction).

11. Calculate the acceleration of a car going from $0$ to $20\,\text{m/s}$ in $5\,\text{s}$.

    $a = \dfrac{v - u}{t} = \dfrac{20 - 0}{5} = 4\,\text{m/s}^{2}$.

12. Write the equation linking force, mass and acceleration (Newton's second law).

    $F = m a$, where $F$ is force (N), $m$ is mass (kg) and $a$ is acceleration ($\text{m/s}^{2}$).

13. What is the relationship between weight, mass and gravitational field strength?

    $W = m g$, where $W$ is weight (N), $m$ is mass (kg) and $g$ is gravitational field strength ($\approx 9.8\,\text{N/kg}$ on Earth).

14. What is friction and what effect does it have on a moving object?

    Friction is a force that opposes motion between surfaces in contact; it acts to slow a moving object down and generates heat.

15. What happens to the motion of an object when the forces on it are balanced?

    The object stays at rest or continues moving at a constant (steady) speed in a straight line — there is no acceleration.

16. Why must a rocket carry its own oxygen supply to burn fuel in space?

    There is no air (no oxygen) in space, so the rocket must carry an oxidiser/oxygen so the fuel can combust.

17. What is a satellite, and give one use of an artificial satellite.

    A satellite is an object that orbits a larger body. Uses include communications (TV/phone), weather monitoring, GPS/navigation and scientific observation.

18. Put these objects in order of increasing size: planet, galaxy, Solar System, Universe, star.

    Planet < star < Solar System < galaxy < Universe.

19. What is a light-year, and is it a unit of distance or time?

    A light-year is the distance light travels in one year; it is a unit of distance (not time).

20. What evidence suggests the Universe began with the Big Bang?

    Distant galaxies are observed moving away from us (redshift), showing the Universe is expanding, which implies it started from a single point — the Big Bang.

21. List, in order, the steps involved in planning a scientific investigation.

    Identify the aim, state the variable to change (independent) and to measure (dependent), identify variables to keep constant, choose apparatus, and plan a safe, fair method.

22. What is a fair test, and why is it important when carrying out experiments?

    A fair test is one where only the independent variable is changed while all other variables are kept the same; it ensures results are valid and any change in the result is due to the variable being tested.

23. Why should measurements in an experiment be repeated, and what should you do with the repeats?

    Repeating reduces the effect of random error and improves reliability; you calculate the average (mean) of the repeated readings.

24. When evaluating results, what is the difference between reliability and accuracy?

    Reliability is how consistent (repeatable) results are when measurements are repeated; accuracy is how close a measurement is to the true value.

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