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8. a) How does the density of particles of the medium change due toincreased pressure when sound travels through it? b) What are suchregions in the medium called? (2m) |
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Answer» Answer: A body covers 20m in 2 sec and 80 m in 4 seconds from the start along a straight LINE. If it is moving with constant acceleration, how much distance will it cover Let the initial VELOCITY of the body be u m/s; and the constsnt acceleration be a m/s². Then displacemet (distance COVERED) of the body after t second is given by s = u t + ½ a t² ———————————-(1) The body covers 20 m in 2s and 80 m in 4 s. 20 = u×2 + ½ a 2²; => 20 = 2 u + 2 a u + a = 10 —————————————(2) 80 = u×4 + ½ a 4²; => 80 = 4 u + 8 a; this gives, u + 2 a = 20 ——————————————(3) Solving (2) and (3) for u and a we get u = 0 m/s and a = 10 m/s² ————————(4) To obtain the distance covered in the next 4s we NEED to find the velocity at the beginning of this interval using, v = u + a t => v = 0 m/s + |
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