When a longitudinal wave moves through a certain medium, the quantity which is transmitted through the medium is
- A.material of the medium only
- B.energy only
- C.both material of the medium and energy
- D.none of the above
Correct answer
Explanation
The correct answer is B, energy only. A wave carries energy from one place to another, while the particles of the medium only vibrate about their fixed positions.
In a longitudinal wave, such as sound in air, the particles of the medium move back and forth along the direction in which the wave travels. They crowd together in compressions and spread apart in rarefactions, and each particle passes its motion on to the next. The disturbance and its energy travel forward, but no particle is carried along with the wave; once the wave has passed, each particle is back where it started. The same holds for transverse waves, such as ripples on water, where a floating leaf bobs up and down but does not move with the ripples.
A is wrong: the material of the medium is not carried forward; it only oscillates.
C is wrong: only energy travels, not matter, so "both" is incorrect.
D is wrong: energy is in fact transmitted, so "none of the above" cannot be right.
Exam tip: waves transfer energy, not matter — sound in air is longitudinal, ripples on water are transverse.
Practice Questions
View allA snowboard pulled up by a tow rope travels at the rate of 5 m/s up a mountain. If 3000 watt of power is used, what force was applied to it ?
- A.50 N
- B.100 N
- C.600 N
- D.15000 N
Show answer
Power equals force times velocity, so the force is 3,000 W divided by 5 m/s, which is 600 N. Power is the rate of doing work: P = W/t. Work is force times distance, W = F × d, so P = F × d/t, and since d/t is the…
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Show answer
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