JAMB 2021 Physics · Question 2

The equation of a wave traveling along the positive x-direction is given by; y = 0.25 x 10 ^ -3 sin (500t…

Question

The equation of a wave traveling along the positive x-direction is given by; y = 0.25 x 10−3^{-3} sin (500t - 0.025x). Determine the angular velocity of the wave motion.

  1. A.0.25 x 10−3^{-3}rads−1^{-1}
  2. B.0.25 x 10−1^{-1}rads−1^{-1}
  3. C.5.00 x 102^{2}rads−1^{-1}
  4. D.2.50 x 103^{3}rads−1^{-1}

Answer: C. 5.00 x 102^{2}rads−1^{-1}

Explanation written with AI and checked against the answer key

1. Analyze the Question

You are given the wave equation y=0.25×10−3sin⁡(500t−0.025x)y = 0.25 \times 10^{-3} \sin(500t - 0.025x) and asked to find the angular velocity (also known as angular frequency, denoted by ω\omega).

2. Explain the Concept

The standard equation for a progressive wave traveling in the positive x-direction is:

y=Asin⁡(ωt−kx)y = A \sin(\omega t - kx)

Where:

  • AA is the amplitude.
  • ω\omega is the angular velocity (angular frequency) in rads−1\text{rads}^{-1}.
  • tt is the time.
  • kk is the wave number.
  • xx is the displacement.

By comparing the given equation to the standard form, you can identify the value of ω\omega by looking at the coefficient of tt.

3. Show the Solution

Given equation:

y=0.25×10−3sin⁡(500t−0.025x)y = 0.25 \times 10^{-3} \sin(500t - 0.025x)

Standard equation:

y=Asin⁡(ωt−kx)y = A \sin(\omega t - kx)

By direct comparison:

  • ω=500\omega = 500

To express 500500 in standard scientific notation as shown in the options:

500=5.00×100=5.00×102500 = 5.00 \times 100 = 5.00 \times 10^2

Therefore, the angular velocity ω=5.00×102 rads−1\omega = 5.00 \times 10^2 \text{ rads}^{-1}.

4. Identify the Answer

Comparing our result to the options provided: A. 0.25×10−3 rads−10.25 \times 10^{-3} \text{ rads}^{-1} B. 0.25×10−1 rads−10.25 \times 10^{-1} \text{ rads}^{-1} C. 5.00×102 rads−15.00 \times 10^2 \text{ rads}^{-1} D. 2.50×103 rads−12.50 \times 10^3 \text{ rads}^{-1}

The correct option is C.

5. Tip

When you see a wave equation, don't let the numbers intimidate you! Always write the standard equation (y=Asin⁡(ωt−kx)y = A \sin(\omega t - kx)) directly above or below the given equation. This makes it easy to "map" the values: the number attached to tt is always your angular velocity (ω\omega), and the number attached to xx is always your wave number (kk).

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