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# Relative Kinematics, Bored Child at Airport

APPHMC-7NVVKE

At an airport, a child starts to walk backward on a moving platform. The child accelerates with $a = -0.5\text{ m/s}^{2}$ relative to the platform.

The platform moves with a constant speed $v = +1.0\text{ m/s}$ relative to the stationary floor.

In $4.0\text{ s}$ how much will the child have been displaced relative to the floor?

A

$8\text{ m}$

B

$4\text{ m}$

C

$3\text{ m}$

D

$0\text{ m}$

E

$-4\text{ m}$