Waves worksheet - Free Printable

Here is the complete, step-by-step solution to all three questions from your “Waves” worksheet.

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## Question 1: Which sentence is correct? Tick one correct box for each type of wave

We need to evaluate each statement based on physics principles.

✔ Light Waves:

- ✘ Light cannot travel through water → False. Light *can* travel through water (that’s why we can see underwater, though it bends and dims).
- ✘ Light cannot travel through a vacuum → False. Light travels *best* in a vacuum — it doesn’t need a medium.
- ✔ Light can travel through a vacuum → TRUE. This is a key property of electromagnetic waves.
- ✘ Light is a longitudinal wave → False. Light is a transverse wave (vibrations perpendicular to direction of travel).

→ ✔️ Correct choice for light: “Light can travel through a vacuum”

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✔ Sound Waves:

- ✘ Sound cannot travel through water → False. Sound travels *very well* through water (faster than in air!).
- ✔ Sound cannot travel through a vacuum → TRUE. Sound needs a medium (solid, liquid, gas) to propagate; no medium = no sound.
- ✘ Sound can travel through a vacuum → False.
- ✘ Sound is a transverse wave → False. Sound is a longitudinal wave (particles vibrate parallel to direction of wave).

→ ✔️ Correct choice for sound: “Sound cannot travel through a vacuum”

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✔ Water Ripples (Surface Waves):

- ✘ Water ripples travel faster than light → False. Nothing travels faster than light (~3×10⁸ m/s). Water ripples are very slow (meters per second).
- ✘ Water ripples travel faster than sound → False. Sound in water travels ~1500 m/s; water ripples are much slower.
- ✘ Water ripples are longitudinal waves → False. Surface water waves are a combination, but primarily transverse (the duck moves up/down while wave moves forward).
- ✔ Water ripples are transverse waves → TRUE (for practical purposes at this level — the motion of particles is mostly perpendicular to wave direction).

→ ✔️ Correct choice for water ripples: “Water ripples are transverse waves”

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✔ Final Answer for Question 1:

- ☑️ Light can travel through a vacuum
- ☑️ Sound cannot travel through a vacuum
- ☑️ Water ripples are transverse waves

*(Note: The question says “tick one correct box for each type of wave”, so you should tick exactly these 3 boxes.)*

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## Question 2: Complete the following sentences

a) Waves transfer energy between one place and another.
*(Waves carry energy without transferring matter.)*

b) If the vibrations of a wave are at right angles to the direction of travel of a wave, it is called a transverse wave.
*(e.g., light, water ripples)*

c) If the vibrations of a wave are parallel to the direction of travel of a wave, it is called a longitudinal wave.
*(e.g., sound waves)*

d) The speed of a wave is measured in metres per second (m/s).
*(Standard SI unit for speed)*

e) The frequency of a wave is how many waves (or cycles) occur in a second. Frequency is measured in hertz (Hz).
*(1 Hz = 1 cycle per second)*

f) Waves can be reflected and refracted.
*(Also: diffracted, interfered — but “refracted” is the most common paired term with “reflected”)*

g) The wavelength of a wave is the distance between two successive crests or troughs.
*(Or “compressions” and “rarefactions” for longitudinal waves — but for general use, crests/troughs are fine.)*

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✔ Final Answers for Question 2:

a) energy
b) transverse
c) longitudinal
d) metres per second (m/s)
e) waves (or cycles); hertz (Hz)
f) refracted
g) distance; crests; troughs

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## Question 3: Distance to the Moon using laser beam

> A laser beam is sent to the Moon and bounces back in 2.6 seconds. Speed of light = 300,000,000 m/s. What is the distance to the Moon?

Step-by-step:

The time given (2.6 s) is for the round trip: Earth → Moon → Earth.

So, the one-way time = 2.6 s ÷ 2 = 1.3 seconds

Use formula:
Distance = Speed × Time

Distance to Moon = 300,000,000 m/s × 1.3 s
= 390,000,000 metres
= 390,000 km (since 1 km = 1000 m)

*(Note: Actual average Earth-Moon distance is ~384,000 km — close enough for this problem!)*

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✔ Final Answer for Question 3:

390,000,000 metres or 390,000 km

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## 📝 Summary of All Answers:

Question 1:

- ☑️ Light can travel through a vacuum
- ☑️ Sound cannot travel through a vacuum
- ☑️ Water ripples are transverse waves

Question 2:

a) energy
b) transverse
c) longitudinal
d) metres per second (m/s)
e) waves (or cycles); hertz (Hz)
f) refracted
g) distance; crests; troughs

Question 3:

390,000,000 metres (or 390,000 km)

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Let me know if you’d like diagrams or further explanations!