Unbalanced forces act on an object when the total force acting on it is not zero. In the scenarios you've provided:
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Two people stand on the same side of a large tire. One person pushes the tire and the other pulls the tire with equal force.
Here, the forces are acting in opposite directions, and since they are equal in magnitude but opposite in direction, they cancel each other out, resulting in balanced forces. -
Two people stand on opposite sides of a large tire. Both people push the tire with equal force.
In this case, the forces are equal and in opposite directions, thus these forces cancel each other out and the tire remains balanced. -
Two people stand on opposite sides of a large tire. Both people pull the tire with equal force.
Similar to the previous cases, both forces are equal and opposite, resulting in balanced forces. -
Two people stand on the same side of a large tire. Both people pull the tire with equal force.
In this scenario, both people are pulling in the same direction, which means that the forces add up. As a result, this creates an unbalanced force on the tire.
Thus, the situation in which unbalanced forces are acting on an object is option 4, where both people pull the tire with equal force from the same side.