Parallel forces do not cause rotation. This is because when forces are applied parallel to an axis, they do not produce any turning effect or moment about that axis. To understand why this is the case, let’s delve into the concept of moments and how they contribute to rotation.
In physics, a moment is a measure of the turning effect of a force about a particular axis or point. It is calculated by multiplying the magnitude of the force by its perpendicular distance from the axis of rotation. The greater the moment, the stronger the turning effect.
When a force is applied parallel to an axis, its moment about that axis is zero. This is because the perpendicular distance between the line of action of the force and the axis is zero. In other words, there is no lever arm for the force to generate a turning effect.
To illustrate this, let’s consider the example of a door. When we apply a force parallel to the door, such as pushing it open or shut, the door does not rotate about the hinge. This is because the force is acting parallel to the axis of rotation, which is the hinge in this case. As a result, the moment about the hinge is zero, and the force does not cause any rotation.
To further clarify, imagine you are pushing a door open by applying a force parallel to it. As you push, you are essentially exerting a force that is parallel to the axis of rotation (the hinge). Since there is no perpendicular distance between the line of action of the force and the hinge, the moment about the hinge is zero. As a result, the door does not rotate.
Similarly, if you apply a parallel force to a wheel, for example, by pushing it along its axis, the wheel will not rotate. The force is acting parallel to the axis of rotation, and therefore, the moment about the axis is zero.
It is important to note that in order for forces to cause rotation, they must have a non-zero moment about the axis of rotation. This requires the forces to have a component that is not parallel to the axis. Only when there is a perpendicular distance between the line of action of the force and the axis, can the force generate a turning effect and cause rotation.
Parallel forces do not cause rotation because their moment about the axis of rotation is zero. Without a non-zero moment, the forces do not produce any turning effect and therefore do not result in rotation.