Biomechanics: Angular Motion

Question 1

Define angular motion

Answer 1

Movement/rotation around a fixed point or axis

Question 2

What is an off-centre force also referred to as?

Answer 2

An eccentric force

Question 3

What does angular motion occur as a result of?

Answer 3

Torque

Question 4

How can moment of force/torque be calculated?

Answer 4

Force x Perpendicular distance from the fulcrum (newton metres) (newtons)

Question 5

Describe Newton’s 1st Law of Angular Motion

Answer 5

A body will continue rotating/spinning with a constant angular velocity unless acted upon by an external torque/rotational force.

Question 6

Describe Newton’s 2nd law of angular motion

Answer 6

The rate of change of angular momentum of a body is directly proportional to the force causing it and the change takes place in the direction in which the force is applied.

Question 7

Describe Newton’s 3rd law of angular motion

Answer 7

When a force is applied by one body to another, the second body will exert and equal and opposite force on the other body.

Question 8

Define angular displacement

Answer 8

The smallest change in angle between the start and finish point of a rotation

Question 9

What is the unit of measurement for angular displacement

Answer 9

Radians/r or degrees /°

Question 10

What is the definition for angular velocity?

Answer 10

The rate of rotation around an axis of rotation

Question 11

Define angular acceleration

Answer 11

The rate of change of angular velocity

Question 12

What is the unit of measurement for angular velocity?

Answer 12

Radians per second (rad/s)

Question 13

What is the unit of measurement for angular acceleration?

Answer 13

Rad/s2

Question 14

Identify A, B and C in the picture

Answer 14

A - Angular Momentum
B - Angular Velocity
C - Moment of Inertia

Question 15

Define angular momentum

Answer 15

Angular momentum is the quantity of rotation a body possesses and is a product of moment of inertia and angular velocity, so remains constant.

Question 16

Define angular velocity

Answer 16

Angular velocity is the rate of rotation of a body around its axes of rotation.

Question 17

Define moment of inertia

Answer 17

Moment of inertia is a body’s reluctance to rotation/

Question 18

What is the relationship between angular momentum, angular velocity and moment of inertia

Answer 18

Angular Momentum = Angular Velocity x Moment of Inertia

Question 19

What two factors does moment of inertia depend upon?

Answer 19

Mass of the body/object
Distribution of mass from axis of rotation

Question 20

Explain how mass of an object affects moment of inertia

Answer 20

The greater the mass, the greater the resistance to change and therefore, the greater the moment of inertia

Question 21

Explain how the distribution of mass from an axis of rotation impacts moment of inertia

Answer 21

The closer the mass is to the axis of rotation, the lower the moment of inertia. The further away mass is from the axis of rotation, the higher the moment of inertia.