Biomechanics

Question 1

What is kinematics vs kinetics

Answer 1

Kinematics = analysis of movement

Kinetics = analysis of force

Question 2

What plane is the frontal axis perpendicular to?

Answer 2

Sagittal plane

Question 3

Terms for:

1. Movement in one dimension
2. In two dimensions
3. Motion about an axis
4. Movement involving a combination of the above

Answer 3

1. Rectilinear motion
2. Curvilinear motion
3. Angular or rotational motion
4. General motion

Question 4

What is the unit of torque?

Answer 4

N/m

Question 5

What is moment of inertia?

Answer 5

The resistance to angular movement (rotation) - angular equivalent to mass

Question 6

Conversion degrees to radians

Answer 6

360 degrees = 2 pi radians

Question 7

What is graphical differentiation?

Answer 7

Drawing a tangent to the curve and calculating the gradient of the tangent.

Question 8

what impact does errors in recording of displacement data have on calculation of velocity and acceleration using that data?

What kind of technique (giving an example) is used to deal with this?

Answer 8

Small differences/errors are amplified.

‘Noisy’ data should be smoothed e.g. plotting a best fit graph.

Question 9

If a displacement graph is concave upwards what does this mean in terms of acceleration?

Answer 9

Positive acceleration

Question 10

What does EAUM stand for?

Answer 10

Equations of uniformly accelerated motion

Question 11

First EUAM?

Answer 11

v2 = v1 + (a . t)

Question 12

Second EUAM?

Answer 12

d = (v1 . t) + (1/2a . t^2)

Question 13

Third EUAM?

Answer 13

d = (v2^2 - v1^2)/2a

Question 14

Quadratic formula?

Answer 14

Question 15

Formula for horizontal range (based on velocity and angle of projection)

Answer 15

R = V^2 . sin (2.theta)/g

Question 16

Sine double angle formula

Answer 16

Cos theta . Sine theta = sin (2 . theta)/2

Question 17

Working definition of force from a mechanical point of view?

Answer 17

“That which pushes or pulls either by direct contact or by action at a distance

Question 18

Newton’s second law?

Answer 18

The acceleration of a body will be directly proportional to the force acting and the mass of that body.

F = m . a

Question 19

Difference between mass and weight and how to calculate weight/units measured in

Answer 19

Mass is scalar vs weight which is a vector

A person with a mass of Wkg will have a weight of 9.81W N (on Earth)

Question 20

Newton’s third law?

Answer 20

Every force has an equal in magnitude and opposite in direction reaction force

Question 21

What is the equation for friction?

How is this affected by area of contact?

Answer 21

Friction = mu x N

where:
mu = coefficient of friction
N = normal reaction force of the body (the perpendicular force)

Unaffected by area of contact

Question 22

What is static friction vs dynamic friction?

Answer 22

When the body remains still on the surface whilst a force is being applied - static friction

Once motion starts and the friction is overcome - dynamic friction

Question 23

Newton’s first law?

Answer 23

Every body continues in its state of rest or uniform motion in a straight line except when it is compelled to change its state by an external force.

Question 24

What is the formula for the coefficient of friction with respect to the angle of the surface to the horizontal?

Answer 24

Tan theta

Question 25

What is the definition of a moment?

Answer 25

A force acting around a fixed axis

Question 26

What are the names for the two forces acting in a lever system?

Answer 26

Resistance force

Effort force

Question 27

What are the three classes of lever?

Answer 27

1st class - effort and resistance forces are on opposite sides of the fulcrum

2nd class - effort and resistance forces are on the same side of the fulcrum, with the resistance force between the effort force and the fulcrum

3rd class - as for 2nd class but the effort force is between the resistance force and the fulcrum

Question 28

What is the formula for mechanical advantage?

Answer 28

MA = Effort arm distance/Resistance arm distance

Question 29

What are the benefits vs disadvantages of class 3 vs class 2 levers

Answer 29

Disadvantage - mechanical disadvantage with force being applied closer to the fulcrum - much greater force required

Advantage - small movement of muscle required to generate large movement in lever quickly

Question 30

Formula for moment?

Answer 30

Moment = F . d

Where:
F = Force
d = Shortest (perpendicular) distance between line of action of the force and the axis of rotation

Question 31

Which direction of moment (with respect to the axis of rotation) is denoted by positive moment?

Answer 31

Anti-clockwise

Question 32

What is the impulse momentum relationship?

Answer 32

F . delta (t) = delta (v) . m

Question 33

What are the two commonly used methods of numerical integration and what assumptions do these both rely on?

Answer 33

1. The Trapezium Rule
2. Simpson’s rule

Both rely on the assumption that the data points are relatively close together and the shape of the curve between the two data points can be assumed to have a particular form

Question 34

What form does Simpson’s rule assume exists between the relevant points

Answer 34

A parabolic curve exists between 3 points

Question 35

What is the formula for Simpsons rule?

Answer 35

Area = delta (x) / 3 . (y0 + 4 . y1 + y2)

where delta (x) is the change in time between two points in the curve (y0 and y1 or y1 and y2)