BM - stability and angular motion in physical activity

Question 1

What is angular motion?

Answer 1

when a body or part of a body moves in a circle or part of a circle about a particular point called the axis of rotation.

Question 2

What is stability?

Answer 2

the ability of a body to return to equilibrium or its original position after being displaced.

Question 3

What is, “the point at which the body is balanced in all directions”

Answer 3

The centre of mass

Question 4

Explain the lever system

Answer 4

a rigid structure, hinged at one point (fulcrum) and to which two forces (load and effort) are applied at two other points.

Question 5

What is the, “the fixed point of rotation about which the lever moves, E.G. joint” called?

Answer 5

Fulcrum

Question 6

What is the, “the resistance or weight to be moved, E.G. the weight of the body part being moved” called?

Answer 6

Load

Question 7

What is the, “the force being applied that causes the lever to move, E.G. the agonist muscle in the body” called?

Answer 7

Effort

Question 8

Define ‘movement of force’.

Answer 8

the effectiveness of a force to produce rotation about an axis. It is the product of the size of the force multiplied by the distance of the force from the fulcrum.

Question 9

What is the axis of rotation?

Answer 9

an imaginary line/point about which the body, or part of the body, rotates.

Question 10

What is the principle axis of rotation?

Answer 10

an axis of rotation that is directed through the body’s centre of mass.

Question 11

What is a rad?

Answer 11

the unit of measurement for angular distance and angular displacement.

Question 12

What is “the angle through which a body has rotated about an axis in moving from the first position to the second”?

Answer 12

Angular distance

Question 13

Define angular displacement.

Answer 13

the shortest change in angular position. It is the smallest angle through which a body has rotated about an axis in moving from the first position to the second.

Question 14

What is the difference between angular speed and angular velocity?

Answer 14

Angular speed is the angular distance travelled in a certain time; angular velocity is the angular displacement travelled in a certian time.

Question 15

Define angular momentum

Answer 15

the quantity of angular motion possessed by a rotating body. It is the product of movement of inertia multiplied by angular velocity.

Question 16

Define moment of inertia

Answer 16

the resistance of a rotating body to change its state of angular motion. All bodies will initially resist rotation and then, once they are rotating, will want to continue to turn about their axis of rotation.