Moment Flashcards
What is a moment?
The turning effect of a force about a pivot.
Formula:
* Moment = Force × Perpendicular Distance from Pivot
What happens if a force acts on the pivot?
The perpendicular distance d = 0, so the moment = 0.
What happens if the total moment clockwise is greater than the total moment anticlockwise?
The object will turn clockwise.
What happens if the total moment clockwise is less than the total moment anticlockwise?
The object will turn anticlockwise.
What happens if the total moment clockwise equals the total moment anticlockwise?
The object is balanced and in equilibrium.
What are the two conditions for an object to be in equilibrium?
No resultant force acts on the object:
* Force up = Force down
* Force right = Force left
No resultant moment acts on the object:
* Total Moment Clockwise = Total Moment Anticlockwise
What are the steps to solve a moment problem?
- Calculate the moment caused by all given forces.
- Determine which forces are clockwise and which are anticlockwise.
- Use Total Moment Clockwise = Total Moment Anticlockwise to solve for missing forces or distances.
How do you calculate the force acting on a pivot?
Use the rule Force up = Force down (since the force direction is downward).
What is the center of mass?
The point at which the weight of an object acts.
How can you find the center of mass practically?
Move the object over a pivot until it balances. That point is the center of mass.
How can you find the center of mass for regular shapes?
The center of mass is located at the center of the 2D or 3D shape.
How can you find the center of mass for irregular shapes?
- Hang the object from a pin at any point.
- Use a plumbline to draw a line of weight.
- Repeat from at least three different points.
- The point of intersection of the lines is the center of mass.
Where is the center of mass in irregular objects with uneven weight?
It is shifted towards the heavier parts.
What factors increase the stability of an object?
- Lower center of mass (closer to the ground).
- Larger base area.
- The line of weight must be within the base area of the object.
What is the SI unit for moment, and how is moment defined?
The SI unit for moment is the Newton-meter (N·m). Moment is defined as the force multiplied by the perpendicular distance from the pivot.
