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A Level · AS · multiple choice

AS Level foundations · Question 4

AS Level foundations · Original GioPhysics question with a detailed, mark-by-mark answer guide.

Demand
routine
Marks
1
Topics
1
Answer
Complete
A stationary wave of four loops on a string fixed at both ends1.2 m
Fig. 4.1A string is stretched horizontally between two fixed supports drawn as hatched blocks, with the distance between them marked 1.2 m. The stationary wave on the string is drawn as a solid curve showing four loops between the supports, and the opposite extreme of the motion is drawn dashed over it, so the string is still at the two fixed ends and at three points in between while the loops vibrate.
multiple choice1 mark

A stationary wave is set up on a stretched string of length 1.2 m fixed at both ends. Four loops are seen between the fixed ends and the frequency is 150 Hz. What is the speed of the progressive waves on the string?

  1. A

    22.5 m s⁻¹

  2. B

    45 m s⁻¹

  3. C

    90 m s⁻¹

  4. D

    180 m s⁻¹

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Answer overviewCorrect answer: C — 90 m s⁻¹
01

Answer and reasoning

1 mark
How to approach it

Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.

  1. 1

    The correct choice is C: 90 m s⁻¹

  2. 2

    Each loop is half a wavelength, so four loops make two wavelengths and λ = 0.60 m. D treats each loop as a whole wavelength; B and A halve again.

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