b. Objects W and Y have balanced forces, and objects X and Z have unbalanced forces.
Explanation:
An object is said to have balanced forces if the resultant of the forces acting on it is zero. This situation occurs, for instance, when the sum of the forces on the vertical direction is zero and the sum of the forces on the horizontal direction is zero as well.
For the objects in the table, we see that:
- Object W: the resultant on the vertical direction is zero, because we have two opposite forces with same magnitude (30 N), so they cancel each other. Also, the resultant on the horizontal direction is zero, because we have two opposite forces with same magnitude (20 N), so they cancel each other.
- Object X: the resultant on the vertical direction is zero, because we have two opposite forces with same magnitude (15 N), so they cancel each other. However, the resultant on the horizontal direction is NOT zero, because we have two opposite forces but with different magnitude (35 N and 25 N), so they do not cancel each other, and they make a net force of 35 N - 25 N=10 N.
- Object Y: the resultant on the vertical direction is zero, because we have two opposite forces with same magnitude (60 N), so they cancel each other. Also, the resultant on the horizontal direction is zero, because we do not have forces along this direction.
- Object Z: the resultant on the vertical direction is zero, because we have two opposite forces with same magnitude (45 N), so they cancel each other. However, the resultant on the horizontal direction is NOT zero, because the net force is 22 N, not balanced from the other direction.
Therefore, objects W and Y have balanced forces, and objects X and Z have unbalanced forces.
of the wave is 160 m, and this is the distance between two consecutive crests. The boat is located at a crest of the wave, this means that the first trough is located 80 meters from the boat (because the distance between a crest and a trough is half the wavelength).
