Lectures 12-18 Flashcards by Finn Carrington

Slide 6, lecture 12

To show which way makes radians positive and which way makes radians negative

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Equation for angular displacement

Angular displacement = final angle - initial angle

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Equation for angular velocity

Angular velocity = angular displacement / change in time

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Equation for angular acceleration

Angular acceleration = change in angular velocity / change in time

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Equation for linear velocity

Linear velocity = angular velocity x radius

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Recap lecture 12 bit about radians

DO NOT SAVE THIS TILL NIGHT BEFORE IT IS VERY IMPORTANT

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What is an ”open chain”? (Recap, Slide 17, lecture 12)

Where the distal segment (hand or foot) is free to move in space. Movements occur distal to the moving joint

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What is a “closed kinetic chain”? (Recap Slide 18, lecture 12)

Where the distal segment (hand or foot) is fixed to a solid surface

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Equation for angular displacement

Angular displacement = final angle - initial angle

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Equation for angular velocity

Angular velocity = angular displacement / change in time

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Equation for angular acceleration

Angular acceleration = change in angular velocity / change in time

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What is the linear to angular analogue of mass? (Look is what this means)

Moment of inertia

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What is the linear to angular analogue of force? (Look is what this means)

Torque (moment of force)

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What is the linear to angular analogue of momentum? (Look is what this means)

Angular momentum

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What is the linear to angular analogue of Newton’s laws? (Look is what this means)

Newton’s laws (angular analogues)

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Equation for moment of inertia

Moment of inertia = mass of each particle x squared distance from axis of rotation

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Heavier objects or those with mass distributed away from their axis of rotation are…? (Related to moment of inertia)

Harder to move and difficult to stop

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What is torque?

It is an “angular force”

It is also a vector (has a magnitude and direction

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Look at slide 11

Lecture 13, torque

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Equation for torque

Torque = Force x Moment arm

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What is torque measured in?

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Find units for all equations

On lectures

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Do equation practice with help from recap

Slide 20 - 24, lecture 13

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What is the moment arm?

The shortest perpendicular distance from a force’s line of action to the axis of rotation

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How to measure torque

Slide 5-8, lecture 14

Slides 9-10

Calculating equilibrium

Lever systems, F L E = ???

1 2 3

Example of a first class lever system?

Elbow extension against a resistance

Example of a second class lever system?

Calf raise

Example of a third class lever system?

Bicep curl

What is an advantage of a second class lever system?

The effort arm is greater than the load arm. So a large load can be moved with a relatively small effort

What is the problem with the mechanical advantage of the second class lever?

It means that there is a reduced range of motion (less movement)

What is the mechanical disadvantage of a third class lever system?

The load arm is greater than the effort arm - so it takes a larger effort to lift a relatively small load

What is a benefit of the mechanical disadvantage of a third class lever?

It allows for a greater range of motion (more movement)

Equation for (tangential) linear velocity?

(Tangential) Linear velocity = angular velocity x radius

Centripetal forces

Slide 5, lecture 15, what are the symbols in the equations

Slides 13 - 18, recap (centripetal and centrifugal forces)

Lecture 15

So equation practice throughout all lectures

Lecture 12-18

What is an isometric contraction?

A muscular contraction where the length of the muscle stay the same

What is an isotonic contraction?

A muscular contraction where the length of the muscle changes

What is an isokinetic muscular contraction?

A muscular contraction with the same angular velocity

What is a concentric muscular contraction?

One where the length of the muscle shortens

What is an eccentric muscular contraction?

One where the length of the muscle lengthens (becomes longer)

A downwards movement is normally what type of muscular contraction?

An eccentric one

Recap lecture 16

One of the ones you missed

Recap lecture 15

One of the ones you missed

Newton’s first law of motion

The law of inertia A body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced force

The angular equivalent of Newton’s first law of motion

A rotating body will continue to rotate about its axis of rotation with a constant angular momentum unless acted on by an external torque

Recap what symbols mean

Slide 4, lecture 17

Learn conservation of angular momentum

PE book, page 98, slide 6, lecture 17

Newton’s second law of motion

Law of acceleration A body’s rate of change of momentum is proportional to the force applied to it and it acts in the direction of that force

The angular equivalent of Newton’s second law of motion

The rate of change of angular momentum is proportional to the torque chasing it

Newton’s third law of motion

The law of reaction For every action there is an equal and opposite reaction

Angular equivalent of Newton’s third law of motion

For every torque exerted by a body on another, there is an equal and opposite torque exerted

Equations for Newton’s laws of motion and the angular equivalents

Throughout lecture 17

Recap lecture 18

No pp slides

Definition of moment arm

The moment arm is the shortest perpendicular distance from a force’s line of action to the axis of rotation

How do you convert radians to degrees? (Smaller to bigger number)

Multiply by 360/2pie

How do you convert degrees to radians? (Bigger to smaller number)

Multiply by 2pie/360

How many radians are there in every circle?

2pie radians

Centripetal (radial) acceleration equation

Tangential (linear) velocity squared / radius

What is the unit for centripetal (radial) acceleration?

Radians/second

Equation for centripetal force

Mass x tangential (linear) velocity squared / radius

What does pennation allow for?

Allows more muscle fibres in the muscle, which are able to contribute to producing more force

If you want to move something quickly, what type of muscle fibres do you want?

Longer

What type of muscle giver do you want in order to produce a lot of force?

Shorter and greater physiological cross sectional area

How many degrees are in one radian?

57.3 degrees

Density equation

Density = mass/volume

Does the density of an object have to be higher/lower than the object it is floating in to sink

Higher

What is the equation for angular momentum?

Angular momentum = moment of inertia x angular velocity

Equation for torque in terms of law of reaction

Ta = -Tb

In terms of the force velocity curve, at what point is maximum power achieved?

1/3 of maximum velocity

What does a force through the CoM result in, in terms of rotation

No rotation

What does a force applied around the CoM result in, in terms of rotation

Rotation and linear motion

What does a force couple result in, in terms of rotation

Pure rotation

What type of turning force is an eccentric/off-centre one?

One where force is applied around the CoM

What is a centrifugal force?

It is an outward acting force Equal and opposite to centripetal force Reaction to the centripetal force

What is a centripetal force?

A force that acts on a body moving in a circular path and is directed to the centre

Define conservation of angular momentum

Angular momentum is a conserved quantity which remains constant unless an external eccentric force or torque is applied

Are you more likely to sink or float in a very dense fluid?

Float

Are you more likely to sink or float in a fluid that is not very dense?

Sink

Definition of a radian

A unit of measurement of angles, equal to about 57.3 degrees