Question

A Boeing 747 "Jumbo Jet" has a length of 59.7 m. The runway on which the plane lands intersects another runway. The width of the intersection is 25.0 m. The plane decelerates through the intersection at a rate of 5.4 m/s2 and clears it with a final speed of 53 m/s. How much time is needed for the plane to clear the intersection?

Answer 1

Answer:

t = 1.48 s

Explanation:

As we know that length of the Boeing plane is

$L = 59.7 m$

width of the intersection is given as

$w = 25.0 m$

now we know that deceleration of the plane is given as

$a = -5.4 m/s^2$

Also the final speed of the plane while it clears the intersection is given as

$v_f = 53 m/s$

now we have

$d = (\frac{v_f + v_i}{2}) t$

$(25 + 59.7) = (\frac{53 + v_i}{2}) t$

also we know that

$v_f - v_i = at$

$53 - v_i = -5.4 t$

now we have

$84.7 = (\frac{53 + 53 + 5.4t}{2})t$

by solving above equation we have

$t = 1.48 s$