A block is attached to a ceiling by a spring of force constant $k.$ When pulled down and released, the block undergoes simple harmonic motion. The motion of the block is shown in the time plot.

Which of the choices most closely describes the amplitude A and frequency $f$ of the motion of the block?

$A=4cm$;$f=\frac{1}{16}Hz$

$A=2cm$;$f=16Hz$

$A=4cm$;$f=\frac{1}{8}Hz$

$A=2cm$;$f=\frac{1}{16}Hz$

Which of the equations of motion best describes the motion of the block?

$y(t)=4cos(\frac{t}{8})$

$y(t)=2cos(8t)$

$y(t)=2cos(\frac{t}{8})$

$y(t)=4cos(16t)$

If the mass of the block is $2\mathrm{.}14$ kg $,$ what is the force constant $k$ of the spring?

$k=$

N$/$m