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A man jumps from a building with a source of sound. When he reaches halfway down, he starts the siren of frequency 100Hz. A person standing below him on the ground hears the first sound to be of frequency 120Hz. What is the height of the building? Speed of sound = 330m/s. Take g=9.81m/s2.

A man jumps from a building with a source of sound. When he reaches halfway down, he starts the siren of frequency 100Hz. A person standing below him on the ground hears the first sound to be of frequency 120Hz. What is the height of the building? Speed of sound = 330m/s. Take g=9.81m/s2. Correct Answer 308m

We can find the speed corresponding to the apparent frequency and then use that to find the height of the building. 120 = 100(330)/(330-v) v = 330 – 3300/12 = 55m/s. Using, v2 = 2gh, we can find the height covered by the man. The double of this value will be the height of the building as he is mid-way. 552 = 2*9.81*h h = 154m Height of building = 2h = 308m.

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