Posted by **CR** on Sunday, February 20, 2011 at 11:27pm.

A Boeing 747 "Jumbo Jet" has a length of 59.7m. The runway on which the plane lands intersects another runway. The width of the intersection is 25.0m. The plane decelerates through the intersection at a rate of 5.7 m/s(squared) and clears it with a final speed of 45.0 m/s. How much time is needed for the plane to clear the intersection?

- Physics -
**Henry**, Tuesday, February 22, 2011 at 12:30pm
d(tot) = 25 + 59.7 = 84.7m.

Vf^2 = Vo^2 + 2*(-5.7)84.7 = (45)^2,

Vo^2 - 965.58 = 2025,

Vo^2 = 2025 + 965.58 = 2990.58,

Vo = 54.7m/s.

Vf = Vo + at,

Vf = 54.7 - 5.7t = 45,

54.7 - 5.7t = 45,

-5.7t = 45-54.7 = -9.7,

t = -9.7 / -5.7 = 1.70s.

- Physics -
**swag**, Sunday, October 2, 2011 at 7:23pm
1.7 seconds

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