Awave travels at a frequency of 387 hz. what is
the period of the wave?

¹/₃₈₇ second

Explanation:

The period of a wave is the reciprocal of its frequency.

So, simply, the frequency is ¹/₃₈₇ second(s), as that is the reciprocal of the frequency, 387 Hz.

where are the vectors ?

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards