Turning Effect Of Forces Chapter 4 Class 9 Physics KPK Board MCQs | Class Nine Physics Chapter 4 MCQs KPK Board

For an object to be fully stable, forces and moments must both be balanced.

Opposite forces subtract, and the direction is that of the larger force.

Forces in the same direction add up directly.

Adding forces gives one resultant force which replaces all individual forces.

Torque = Force × Perpendicular distance from the pivot.

A longer arrow means a stronger force, and a shorter arrow means a weaker force.

Torque (moment of force) causes an object to rotate around a pivot or axis.

Symmetrical objects (like spheres, cubes) have their center of mass at their geometric center.

A force applied far from the pivot (hinges) creates a larger moment, making the door easier to open.

When all forces balance each other, the net (resultant) force becomes zero, and the object is in equilibrium.

The turning effect or rotational effect produced by a force is known as the moment of force.

Stability means an object resists tipping or falling and comes back to equilibrium after a small displacement.

The arrow tells us which way the force is acting.

Center of mass is the point where the entire mass of an object is considered to be concentrated.

More mass pulls the center of mass toward the heavier part of the object.

Balanced forces result in no change in motion.

High center of gravity and narrow base make tipping easier, causing instability.

Breaking a force into components helps us analyze motion more easily.

Both forces act in the same direction, so they add up (5 N + 3 N).

A larger distance from the pivot increases the moment of force, making it easier to turn.

A spanner uses torque to tighten or loosen nuts by applying force at a distance.

A force diagram represents all forces acting on an object using arrows that show direction and size of each force.

A steering wheel is turned by two hands applying opposite forces, forming a couple.

Torque is measured in Newton meter, meaning force multiplied by distance.

Weight is the force due to gravity and always acts downward toward the Earth.

A uniform rod has equal mass throughout, so its center of mass lies at the midpoint.

Any angled force can be resolved into two components at right angles to each other.

The book has low center of gravity and wide base, so it is stable.

Like torque, the moment of a couple is measured in Newton meter.

A larger distance creates a greater turning effect, making rotation easier.

A wider base increases stability by providing better support and balance.

The book does not move or rotate because all forces and moments are balanced.

Balanced forces result in no change in motion.

When a force is resolved, the smaller forces are called its components.

The rotational effect of a couple is known as the moment of a couple.

A spanner works on the principle of moment of force, helping to rotate the nut with less effort.

Equal and opposite forces cancel each other, producing balanced forces.

Translational equilibrium occurs when forces in all directions cancel out.

Resolution means breaking a single force into two perpendicular forces (usually horizontal and vertical).

The center of mass is the point where an object can be balanced.

A couple does not move an object forward; it only rotates the object.

Objects with low center of gravity are harder to topple, making them more stable.

This condition ensures there is no net turning effect on the object.

Moment = Force × Perpendicular distance from pivot.

For simplicity, forces are resolved into vertical and horizontal components.

A couple is formed by two forces equal in size, opposite in direction, and parallel, producing rotation.