Chapter5- Trning Effects of Forces

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Negotiation

Szerző: Stu Russell

BIOMECHANICS

Szerző: Kimberly Harrison

forces

Szerző: Taninette Wong

Turning Efffect of Forces

Szerző: Raj Kuthrapoli

Turning effect of forces

Definition of the Moment of a Force

Moment of a Force= F x d

Definition: The moment of a force(M) about a point or pivot(O) is the product of the force(F) and the perpendicular distance(d) from the line of action of the fprce to the point/pivot.

Stability and CG

Neutral equilibrium

when a body remanis wherever it is displaced

Unstable equilibrium

when a body continues to move away from its original position after it is being slightly displaced

Stable equilibrium

when a body is able to return to its original position after being displaced slightly

Principle of Moments

When a body is in equilibrium, the sum of clockwise moments about the balance point or pivot = to the sum of anti-clokwise moments about the same point

Total clockwise moments about the same point = total anti-clockwise moments about a point

Moment

The turning effect(or moment) of a force depends on

b) Perpendicular distance between the point of the application of the force and the pivot

a) Magnitude of the force

Definition: The moment of a force is the turning effect of a force about a point

Centre of Gravity(CG)

Centre of gravity of a regular-shaped object

E.g metre rule. The centre of gravity is its centre(or geometrical centre)

Centre of gravity of a irregular-shaped object

centre of gravity is always vertically below the pivot(point of suspension) when it is hanging freely about it

Definition: The centre of gravity(CG) of a body is that point where the whole weight of the body seems to act

FORCES

friction

contact force

always act in an opposite direction to the force applied on an object

Newton's law of motion

3rd law of motion

action-reaction forces

occurs when 2 forces are present

2nd law of motion

unbalanced forces

Net F=ma

1st law of motion

balanced forces

Body continues to move at constant spped in a straight line unless an unbalanced force acts on it.

effects of forces

stop a moving object

move a stationary object

change the shape of an object

change the direction of an object

Decelerates an object

Accelerates an object