A(n) is a material that causes a wave to bounce off of it

Answer;

A barrier, a surface or a boundary

Explanation;

Reflection is the property waves that occurs due to the bouncing back of a wave after it strikes a barrier.

Reflection involves change in direction of a wavefront at an interface between two different media such that the wavefront returns into the medium from which it originated. In other words, the direction of the wave changes when they bounce of a barrier or a surface.

overcharge is the right answer system

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