Moment Flashcards
What is a moment (turning effect) and how is it calculated?
A moment is the turning effect of a force about a pivot.
Moment = Force × Perpendicular Distance from Pivot.
What steps are followed to solve a problem involving moments?
- Determine the pivot position.
- Identify forces acting at the pivot (no moment).
- Determine the moment’s direction (clockwise or anti-clockwise).
- Measure the perpendicular distance between the force and the pivot.
What is the principle of moments for a balanced system?
For a system in equilibrium:
Clockwise Moment = Anti-clockwise Moment
There is no net turning effect.
What does ‘uniform’ mean in the context of moments?
If a body is uniform, its weight acts at its center, and the center of gravity is at the middle.
How is the center of mass determined for regular and irregular shapes?
• Regular shapes: The center of mass is at the geometric center.
• Irregular shapes: Use a plumb line and mark intersecting lines to locate the center of mass.
What increases the stability of an object?
• A wider base area
• Lowering the center of mass
For stability, the line of weight action must pass through the base.
What are common issues in equilibrium experiments and their solutions?
• Load falls: Secure it with tape.
• Balance cannot be achieved: Repeat and adjust the positions.
• Scale obscured by load: Adjust viewing angles or reposition.
How can equilibrium be identified in a system?
A system is in equilibrium if:
• Net moment = 0
• Clockwise and anti-clockwise moments are equal
• It is at rest or moving with constant speed.
How can the center of mass affect the turning effect of a body?
• If the pivot is at the center of mass, the weight creates no moment.
• If the pivot is away from the center of mass, the weight must be considered when calculating moments.
What is the definition of the center of mass (gravity)?
The center of mass is the point where the body’s weight acts, balancing the body. It coincides with the pivot in uniform bodies.
