chapter 5 - moments

Question 1

moment

Answer 1

product of the force F and the perpendicular distance d from the pivot to the line of action of the force

Question 2

principle of moments

Answer 2

when a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot

Question 3

centre of gravity

Answer 3

an imaginary point where the entire weight of the object seems to act

Question 4

stability

Answer 4

measure of an object’s ability to return to its original position

Question 5

why does an object topple?

Answer 5

when tilted, the line of action of the weight passing through the centre of gravity lies outside the base area, and the clockwise/anticlockwise causes the object to be unable to return to its original position

Question 6

how to increase stability

Answer 6

increase base area (line of action can fall within), lower centre of gravity (add mass)

Question 7

how to find cg of lamina?

Answer 7

1. make a few points on the lamina
2. trace the line formed by hanging a plumb line vertically from a point
3. repeat the step by hanging the plumb line through different points of the lamina and trace the vertical line formed by the plumb line
4. the intersection point of the traced line is the centre of gravity of the lamina

Question 8

when more mass is added to the base, why is the object more stable?

Answer 8

the centre of gravity is now lowered, decreasing the perpendicular distance from the pivot to the line of action if the force. now, the line of action of the force is more likely to pass through the pivot point, causing the object to be more stable