Physics Medium ⚡ 10 Questions ⏱️ ~7 Mins +100 XP

Forces, Energy & Light

Ten questions on the rules everything obeys, each stated in plain language rather than symbols.

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About this topic

This quiz covers the physics that explains everyday experience: why objects keep moving, what a newton and an ohm measure, how fast light travels and what happens when it passes through a prism. It includes the famous results, relativity among them, at the level of what they claim rather than how they are derived. The explanations avoid equations entirely. Everything here can be understood without calculation, which is closer to how physicists describe their own field than most textbooks suggest.

Questions & answers

Forces, Energy & Light: all 10 questions and answers

Every question in this quiz is listed below with its correct answer and the reasoning behind it. Play first if you would rather not see the answers — or read through as a study sheet.

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  1. 1The speed of light in a vacuum is closest to which value?

    • A 30,000 kilometres per second
    • B 3 million kilometres per second
    • C 300,000 kilometres per hour
    • D 300,000 kilometres per second Correct

    Answer: D. 300,000 kilometres per second

    Why: It is about 299,792 kilometres per second, and nothing carrying information travels faster. The value is now fixed by definition and used to define the metre.

  2. 2Newton's first law of motion is chiefly about what?

    • A Gravity
    • B Momentum transfer
    • C Friction
    • D Inertia Correct

    Answer: D. Inertia

    Why: It states that an object keeps doing what it is doing unless a force acts on it. This is counterintuitive on Earth only because friction is always present.

  3. 3What is the SI unit of force?

    • A The pascal
    • B The joule
    • C The newton Correct
    • D The watt

    Answer: C. The newton

    Why: One newton accelerates one kilogram by one metre per second squared. The joule measures energy and the watt measures power.

  4. 4The equation E=mc squared is associated with which physicist?

    • A Niels Bohr
    • B Max Planck
    • C Albert Einstein Correct
    • D Isaac Newton

    Answer: C. Albert Einstein

    Why: Einstein published it in 1905, showing that mass and energy are interchangeable. The enormous value of c squared is why tiny masses release vast energy.

  5. 5Surface gravity on the Moon is approximately what fraction of Earth's?

    • A About the same
    • B About one third
    • C About one half
    • D About one sixth Correct

    Answer: D. About one sixth

    Why: The Moon is far less massive, so its surface pull is roughly a sixth. That is why the Apollo astronauts moved in long bounding steps.

  6. 6Sound generally travels fastest through which medium?

    • A A vacuum
    • B Gases
    • C Liquids
    • D Solids Correct

    Answer: D. Solids

    Why: Closely packed particles pass vibrations along quickly, so solids carry sound fastest. Sound cannot travel through a vacuum at all.

  7. 7What is the unit of electrical resistance?

    • A The ohm Correct
    • B The volt
    • C The coulomb
    • D The ampere

    Answer: A. The ohm

    Why: Resistance in ohms describes how strongly a material opposes current. Volts measure potential difference and amperes measure current.

  8. 8Which subatomic particle carries a negative charge?

    • A The photon
    • B The proton
    • C The neutron
    • D The electron Correct

    Answer: D. The electron

    Why: Electrons are negatively charged, protons positive and neutrons neutral. Chemical behaviour is governed almost entirely by the electrons.

  9. 9Absolute zero corresponds to which temperature?

    • A Minus 100 degrees Celsius
    • B Zero degrees Celsius
    • C Zero degrees Fahrenheit
    • D Zero kelvin Correct

    Answer: D. Zero kelvin

    Why: It is 0 K, or about minus 273 degrees Celsius, the point where particle motion is minimal. It cannot actually be reached, only approached.

  10. 10Passing white light through a prism produces what?

    • A A single brighter beam
    • B A spectrum of colours Correct
    • C Polarised sound
    • D A shadow

    Answer: B. A spectrum of colours

    Why: Different wavelengths bend by different amounts, spreading the light into its components. Newton used this to show white light is a mixture rather than a pure colour.

Frequently asked questions about Forces, Energy & Light

How many questions are in Forces, Energy & Light?

Forces, Energy & Light has 10 questions and takes about 7 minutes to finish. It is rated Medium and sits in our Physics category.

How is Forces, Energy & Light scored?

Each of the 10 correct answers adds 10 XP, up to 100 XP for a clean run. Wrong answers cost you nothing, and your full question-by-question review is shown at the end.

Are the answers to Forces, Energy & Light explained?

Yes. All 10 questions carry a written explanation of why the correct answer is right, so the quiz works as a study sheet as well as a test.

Can I replay Forces, Energy & Light?

Yes, as often as you like. The questions and the answer options are reshuffled on each run, and you can use Practice Mistakes afterwards to retry only the ones you missed. No account is needed to play.

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