Unbalanced forces act on an object when the total force acting on it is not equal to zero, resulting in a change in motion.
Let's analyze the options:
a. Two people stand on opposite sides of a large tire. Both people pull the tire with equal force.
- This results in balanced forces because the forces are equal and opposite, so the net force is zero.
b. 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.
- This results in unbalanced forces because the direction of the forces are different (one in and one out), creating a net force that does not equal zero.
c. Two people stand on the same side of a large tire. Both people pull the tire with equal force.
- This results in balanced forces because the forces are equal, resulting in a net force of zero.
d. Two people stand on opposite sides of a large tire. Both people push the tire with equal force.
- This results in balanced forces as the forces are equal and opposite, resulting in a net force of zero.
Thus, the situation where unbalanced forces are acting on an object is: b. 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.