1. Principle of Moments & Balance

The Principle of Moments says that an object stays balanced if:

Clockwise Moment=Anticlockwise Moment\text{Clockwise Moment} = \text{Anticlockwise Moment}Clockwise Moment=Anticlockwise Moment

If one side has a bigger moment, the object tilts in that direction.

🔹 Example: A seesaw is balanced when both sides have equal weight and distance.

2. Clockwise vs. Anticlockwise Moments

• Clockwise Moment → Rotates an object to the right (↘)

• Anticlockwise Moment → Rotates an object to the left (↖)

• If both moments are equal, the object does not rotate.

🔹 Example: A balanced seesaw does not move because both sides are equal.

3. Everyday Uses of the Turning Effect of Force

✔ Opening a door – Pushing near the handle makes it easier.✔ Seesaw – A heavier person tilts the seesaw.✔ Steering a car – Holding the edge of the wheel gives more control.✔ Rowing a boat – Oars push water to move the boat forward.✔ Using a wrench – A longer wrench makes turning bolts easier.

4. How Levers Work

A lever is a simple machine that turns around a pivot.

Types of levers:1️⃣ Seesaw – Pivot in the middle.2️⃣ Wheelbarrow – Load in the middle.3️⃣ Tweezers – Effort in the middle.

🔹 Example: A wheelbarrow makes lifting heavy loads easier.

5. Why a Longer Wrench Works Better

A longer wrench gives a bigger moment with less force.

Moment=Force×Distance\text{Moment} = \text{Force} \times \text{Distance}Moment=Force×Distance

✔ More distance = More turning power✔ Less effort needed to turn the bolt

🔹 Example: A short wrench needs more strength, but a long one does the job easily.

6. Center of Gravity & Balance

The center of gravity (CoG) is the point where an object’s weight acts.

✔ If you push through the CoG, no rotation happens.✔ If you push away from the CoG, the object tilts.✔ A lower CoG makes an object more stable.

🔹 Example: A racing car is stable because it has a low center of gravity.

7. How Force Direction Affects Rotation

✔ Best way to apply force → Perpendicular (90°) to the object for maximum rotation.✔ Less effective → At an angle.✔ No effect → Along the pivot.

🔹 Example: A door opens best when you push straight, not at an angle.