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A toy rocket is launched vertically from ground level (y = 0.00 m), at time t = 0.00...

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Kelvin12 | eNotes Newbie

Posted September 14, 2013 at 4:29 PM via web

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A toy rocket is launched vertically from ground level (y = 0.00 m),

at time t = 0.00 s. The rocket engine provides constant upward acceleration during the burn phase. At the instant of engine burnout, the rocket has risen to 72 m and acquired a velocity of 30 m/s. The rocket continues to rise in unpowered flight, reaches maximum height, and falls back to the ground with negligible air resistance. The speed of the rocket upon impact on the ground is closest to ...?

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted September 14, 2013 at 4:44 PM (Answer #1)

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A toy rocket is launched vertically from ground level at time t = 0.00 s. The rocket engine provides constant upward acceleration during the burn phase. At the instant of engine burnout, the rocket has risen to 72 m and acquired a velocity of 30 m/s.

As the velocity of the rocket is not zero it continues to rise upwards. The height at which its velocity is 0 is 72 + s where 2*9.8*s = 30^2

=> s = 4500/49

When the rocket falls from 8028/49 m, the velocity on impact is 2*9.8*(8028/49) = v^2

=> v `~~` 56.66 m/s

The speed of the rocket on impact is 56.66 m/s

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