Physics - week 3

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Questions and Answers

Which statement accurately describes the Centre of Gravity (COG)?

The COG remains the same regardless of the orientation of the object.

The COG is a hypothetical point where all mass is considered to be concentrated. (correct)

The COG shifts towards the heavier side when external mass is added. (correct)

The COG is always at the physical center of an object.

What is a characteristic of static equilibrium?

There is no movement, and all forces acting on the body are balanced. (correct)

The COG must always be outside of the base of support.

The body is in continuous motion but remains balanced.

Only external forces need to be considered for balance.

Which factor does NOT affect the stability of an object?

The height of the centre of gravity

The color of the object (correct)

The size of the base of support

The weight of the object

When external mass is applied to one side of an object, how does it generally affect the COG?

The COG shifts towards the side with the additional mass. Signup and view all the answers

What defines a dynamic equilibrium state?

The object is in motion but remains balanced. Signup and view all the answers

What must occur for an object to maintain stability?

The line of gravity must fall within the base of support. Signup and view all the answers

How does increasing the mass of an object affect its stability?

It increases stability. Signup and view all the answers

Which condition will not enhance an object's stability?

An elevated line of gravity. Signup and view all the answers

What happens to the center of gravity (COG) when a person carries a heavy suitcase in one hand?

It shifts upwards and to the right. Signup and view all the answers

What is the effect of adding external mass to a person standing on one leg?

It decreases the base of support. Signup and view all the answers

How can a person effectively relocate their line of gravity during movement?

By leaning in the direction of their intended movement. Signup and view all the answers

Which of the following does NOT contribute to maintaining equilibrium in dynamic movements?

A narrow base of support. Signup and view all the answers

What is the primary impact of a large base of support on the line of gravity?

It allows more freedom of movement without tipping. Signup and view all the answers

What happens to the center of gravity (COG) of an object when it is asymmetrical?

It shifts towards the heavier end of the object. Signup and view all the answers

How does the base of support (BOS) affect the stability of an object?

A larger BOS increases stability. Signup and view all the answers

Which statement is true regarding static and dynamic equilibrium?

Both types of equilibrium exist when forces acting are perfectly balanced. Signup and view all the answers

What affects the location of the center of gravity (COG) in the human body?

The position of body segments. Signup and view all the answers

When a person inclines their trunk forward, where does the COG shift?

It shifts outside the body. Signup and view all the answers

Which factor contributes most significantly to the stability of an object?

The base of support relative to the center of gravity. Signup and view all the answers

What is described as the line running vertically from the center of gravity to the ground?

The line of gravity. Signup and view all the answers

Which condition most directly affects an object's equilibrium?

The combined weight and distribution of mass. Signup and view all the answers

Study Notes

Center of Gravity (COG)

The COG is the hypothetical point where all an object's mass is concentrated.
It's the point where gravity appears to act.
In symmetrical objects, the COG is located at the geometric center.
In asymmetrical objects, the COG is located towards the heavier end.
The COG in the human body is located differently for each body segment.
The COG of the whole body can be found by combining the COG of each segment.
The location of the COG in the human body changes with different postures.
When the trunk is inclined forward, the new COG is located outside the body.

Line of Gravity (LOG)

The LOG is a vertical line that passes through the COG and extends to the ground.
It represents the direction of the force of gravity acting on the object or person.
It can be visualized as a string with a weight on the end, attached to the COG.

Equilibrium

Static equilibrium: A state where an object is at rest.
Dynamic equilibrium: A state where an object is moving at a constant velocity.
Equilibrium occurs when the forces acting on an object are balanced.

Rules of Equilibrium

The larger the base of support (BOS), the more stable the object.
The closer the COG to the BOS, the more stable the object.
An object is not stable unless the LOG falls within the BOS.
The greater the mass of the object, the greater the stability.
The greater the friction between the supporting surface and the BOS, the more stable the object.

Relocation of Center of Gravity

The COG of an object can change depending on the arrangement of segments and distribution of mass.
Adding external mass to the body will shift the COG towards the added weight.
This shift is proportional to the weight added.

Gravity

An external force that acts on all objects.
The force of gravity is the pull of the earth on a body or its segments.
It's a constant force directed towards the center of the earth.
Gravity as a force is a vector quantity.
Point of application: COG
Line of application: Center of mass of the object
Direction: Towards the center of the earth
Magnitude: Equal to gravitational force

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Description

This quiz explores concepts related to the center of gravity (COG), line of gravity (LOG), and equilibrium in both static and dynamic states. Understand how the COG is determined in various objects, including the human body, and the significance of these concepts in physics and biomechanics.