What or the two ends of a magnet called

When using the scientist method, which step comes last?

Consider motion in one dimension. (the sign of the vector quantities is their direction indicator.) an object moves in the positive x-direction with speed 2.9 m/s for 4.5 s. it stops for 3.8 s and then moves in the negative x direction with speed 2.8 m/s for 4 s. what is the total distance traveled by the object in units of meter? enter a number with two digits behind the decimal point.

Which wave would cause destructive interference at every point of the wavelength and completely cancel out the wave?