Class 9 > Unit # 04: Turning Effect of Forces > Like & Unlike Parallel Forces

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Turning Effect of Forces - Like and Unlike Parallel Forces

Q. Define Like and Unlike Parallel Forces with examples.

1. Like Parallel Forces

"The forces that act along the same direction are called like parallel forces."

Like parallel forces can add up to a single resultant force and, therefore, can be replaced by a single equivalent force.

Example:
Many people pushing a car to move it forward. All of these individual pushing forces act along the same direction (line), combining into a single effective force moving the car.

2. Unlike Parallel Forces

"The forces that act along opposite directions are called unlike parallel forces."

These forces can also add up to a single resultant force. However, when a pair of unequal or separated unlike forces do not act along the exact same line, they can be responsible for the rotation of objects (forming a couple). Such unlike parallel forces cannot be replaced by a single resultant force unless balanced by equal and opposite forces directed at different points.

Example:
A ceiling fan suspended from a hook through a supporting rod. The two primary forces acting on it are:

• The weight of the fan acting vertically downwards.
• The tension in the supporting rod pulling it vertically upwards.

These two forces are parallel but opposite to each other, acting along the same line, making them classic examples of unlike parallel forces.

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