Balanced Force Equal pushes, zero motion.

Key Term

Balanced Force

When all forces on an object cancel out, the net force is 0 N. The object stays at rest or moves without changing speed or direction.

Quick check: If the net force on a parked car is zero, will its speed change? (Yes / No)

Tug of Forces

https://asset.sparkl.ac/pb/sparkl-vector-images/img_ncert/AJj6cTCm91OH6lL698t396KROGMkaGltgpA2mQNa.png

Equal pulls cancel out; the block remains still.

Balanced Force on a Wooden Block

A wooden block is tied to two opposite strings, X and Y.

Two students pull the strings with equal strength in opposite directions.

The forces balance, net force \(=0\), so the block stays at rest.

Key Points:

  • Equal magnitude, opposite direction → balanced force.
  • Net force \(0\) keeps the block stationary.
  • If one side pulls harder, balance breaks and the block moves that way.

Box & Friction

Push and friction on a box

Arrows show applied push and opposing friction

Push vs Friction on a Box

Static friction opposes your push and grows with the applied force.

When forces are balanced, the net force is zero and the box stays still.

Key Points:

  • Gentle push: balanced forces (push = friction) → box remains at rest.
  • Moderate push: still balanced, no motion.
  • Push exceeds maximum friction: unbalanced force → box accelerates forward.

Assessment: Balanced Net Force

Question

When forces on an object are balanced, the net force on the object is:

1
0 N
2
10 N to the left
3
10 N to the right
4
Cannot be determined

Hint:

Add the forces — remember opposite directions cancel.

Key Takeaways

⚖️

Net Force Zero

Equal & opposite forces cancel out.

🛑

No Change in Motion

Rest stays rest; moving stays same speed.

🎯

Direction Matters

Forces must act opposite to balance.

🧪

Test with Sliders

Equal arrows → balanced; unequal → moves.