Question

In which situation are unbalanced forces acting on an object

Answer 1

Unbalanced forces act on an object whenever the vector sum of all forces on it is not zero (∑F ≠ 0). That nonzero net force produces acceleration (a change in the object's speed and/or direction) according to Newton's second law: ∑F = ma.

How to tell:
- If the object’s velocity is changing (speeding up, slowing down, or changing direction), forces are unbalanced.
- If forces present do not cancel each other vectorially, they are unbalanced.

Examples:
- A stationary book that starts sliding when you push it (your push exceeds friction).
- A car accelerating when the engine produces more forward force than air resistance and friction.
- A car braking: the backward frictional force exceeds the forward driving force, producing deceleration.
- A ball thrown in a curve: gravity and the contact/air forces don’t cancel, so the path bends.
- An object in free fall (gravity is unopposed by an equal upward force), so it accelerates downward.
- Tug-of-war where one side pulls harder than the other; the rope and players accelerate toward the stronger side.

Simple numeric example:
- Two horizontal forces on a box: 10 N right and 4 N left → net force = 10 − 4 = 6 N right → unbalanced → box accelerates right.

If you want, I can draw a free-body diagram or give more classroom examples/problems.