Ignatius Yeo's answer to sara's Secondary 3 A Maths Singapore question.
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For part i, a is the initial position of the capsule, in this case must be 90meters above ground. It is rotating, so trigonometry is applied. In this case, sine applies and sine curve is maximum at 45 degrees(9min in this case) since 360 degrees is 36 min. Refer to the diagram in the photo for understanding. NOTE: a is not amplitude and b is not the period as you have mentioned.
For part ii, instead of the sine curve starting from 0 or point of origin, it has been shifted 90 meters up. Since question is asking for 0 to 72 min, it must be two waves because 72/36=2. Amplitude is the radius in this case.
For part ii, instead of the sine curve starting from 0 or point of origin, it has been shifted 90 meters up. Since question is asking for 0 to 72 min, it must be two waves because 72/36=2. Amplitude is the radius in this case.
Date Posted:
4 years ago
You can also create two simultaneous equations to prove as shown in the photo. When t is 9 min, maximum height results. When t is 27 min, minimum height results. Applying trigonometry gives the following equations: a+b=170, a-b=10
a=90m, b=80m. Hope it helps:)
a=90m, b=80m. Hope it helps:)
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