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An object starting from rest travels 20 m in first 2 s and 160 m in next 4 s. The velocity of object after 8 s from the start will beA80 m/sB40 m/sC160 m/sD60 m/s |
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Answer» Explanation:From s=ut+ 2 1 at 2 In first 2 s, s=20m 20= 2 1 a(2) 2 =2a a=10 m/s 2 Velocity at the end of 2 s is v=u+at=0+10×2=20m/s In NEXT 4s, s=ut+ 2 1 a ′ t 2 160=20×4+ 2 1 a ′ (4) 2 80=8a ′ a ′ =10 m/s 2 It SHOWS that acceleration is uniform. From v=u+at v=0+10×7=70 m/s Answer: (D) 70 |
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