A simple pendulum is $4\mathrm{.}80$ m long.

$($a$)$ What is the period of simple harmonic motion for this pendulum if it is located in an elevator accelerating upward at $4\mathrm{.}70$ m$/$s$2?$

s

$($b$)$ What is its period if the elevator is accelerating downward at $4\mathrm{.}70$ m$/$s$2?$

s

$($c$)$ What is the period of simple harmonic motion for the pendulum if it is placed in a truck that is accelerating horizontally at $4\mathrm{.}70$ m$/$s$2?$