The velocity of a particle rises uniformly from 0 to 20 m / s in 2 s, stays 20 m / s until t = 4 s and then falls uniformly to 0 at t = 7 s. The distance covered in the last 3 seconds is what fraction

Question

The velocity of a particle rises uniformly from 0 to 20 m / s in 2 s, stays 20 m / s until t = 4 s and then falls uniformly to 0 at t = 7 s. The distance covered in the last 3 seconds is what fraction of the total distance?

TestHub · Accepted Answer

Areas: 0 - 2 s: 2 1 ​ ( 2 ) ( 20 ) = 20 m; 2 - 4 s: 40 m; 4 - 7 s: 2 1 ​ ( 3 ) ( 20 ) = 30 m. Total = 90 m and the last 3 s give 30 m, so the fraction is 3 1 ​ . Option B.

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