Chapter 5: Turning Effect of Forces Flashcards

A set of vocabulary flashcards covering the concepts of torque, the principle of moments, centers of gravity, and stability based on the Chapter 5 physics lecture notes.

Moment of a force (or torque)

The product of the force and the perpendicular distance from the line of action of the force to the pivot.

Moment calculation formula

$Moment = F \times d$, where $F$ is force (in $N$) and $d$ is perpendicular distance from the line of action of force to the pivot (in $m$).

SI unit of the moment

The newton metre ($N \, m$).

Principle of Moments

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

Centre of gravity (c.g.)

The point through which the weight of a body appears to act, for any orientation of the object.

C.G. of uniformly shaped objects

For regular shapes with uniformly distributed mass, the centre of gravity is at the geometric centre or intersection of midpoints/vertices.

Plumbline method

A qualitative method to determine the centre of gravity of non-uniform objects by suspending them from three points to find the intersection of the weight lines.

Stability

The ability of a body to return to its initial position after it has been tilted slightly.

Methods to increase stability

1. Lower the centre of gravity as much as possible. 2. Make the area of the base as wide as possible.

Cause of toppling

A body falls over if tilted so far that the line of action of its weight lies outside the base, producing a net moment that rotates the object away from its upright position.