A particle moving with constant acceleration has speeds 10 m s⁻¹ and 30 m s⁻¹ at positions x = 20 m and x = 120 m respectively. Its speed at x = 200 m is:
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A particle moving with constant acceleration has speeds 10 m s⁻¹ and 30 m s⁻¹ at positions x = 20 m and x = 120 m respectively. Its speed at x = 200 m is:

G1 Physics · Accepted Answer

Between x = 20 m and x = 120 m: 30² − 10² = 2a(100), giving a = 4 m s⁻². From x = 120 m to x = 200 m: v² = 30² + 2(4)(80) = 1540 = 100×15.4. This is not one listed radical. Using the full displacement from x = 20 m to 200 m gives v² = 100 + 2(4)(180) = 1540, so v ≈ 39.24 m s⁻¹.