Biomechanics- unit 1

Question 1

4 Base SI units

Answer 1

Metre (m), second (s), kilogram (kg), kelvin (K)

Question 2

Supplementary SI unit

Answer 2

Radian (radO

Question 3

Derived SI unit

Answer 3

Newton (N) (kg /s squared)

Question 4

M- mega
k- kilo
c- centi
m- milli
μ- micro
n- nano

Answer 4

1000000
1000
0.01
0.001
0.000001
0.000000001

Question 5

SI unit of time

Answer 5

second

Question 6

Convert radians to degrees

Answer 6

multiply by 180/pi

Question 7

Another name for rectangular co ordinate system

Answer 7

Cartesian co-ordinate system

Question 8

What is the origin

Answer 8

The point where all three axes cross (0,0,0)

Question 9

Are planes 2D or 3D

Answer 9

2D

Question 10

Max number of planes that can be mutually at right angles to each other

Answer 10

3

Question 11

Difference between rectangular and polar co ordinates

Answer 11

Rectangular co ordinate systems use displacements relative to perpendicular axes whilst polar co- ordinate systems use a displacement and rotations.

Question 12

2 forms of motion

Answer 12

Linear, rotary

Question 13

Displacement def

Answer 13

Distance with direction- vector quantity

Question 14

Scalar

Answer 14

Magnitude only

Question 15

Vector

Answer 15

Magnitude and direction

Question 16

Speed

Answer 16

rate of change of distance travelled

Question 17

velocity

Answer 17

rate of change of displacement

Question 18

Av velocity

Answer 18

change in displacement / time

Question 19

SI units of velocity

Answer 19

m/s

Question 20

Acceleration

Answer 20

Rate of change of velocity

Question 21

Average acceleration

Answer 21

change in velocity/ time taken

Question 22

two effects of force acting on a body

Answer 22

tend to change the position of the object in space, tend to deform the shape of the object

Question 23

Rigid body mechanics

Answer 23

assume that bodies under consideration can’t be deformed

Question 24

Way of measuring force

Answer 24

Calibrated spring balance

Question 25

SI unit of force

Answer 25

Newton (N)

Question 26

Is force a vector or scalar quantity

Answer 26

Vector

Question 27

Statics

Answer 27

Body not accelerating but may be moving at a constant velocity

Question 28

Static equilibrium

Answer 28

No resultant force acting on the body

Question 29

First condition of static equilibrium

Answer 29

The sum of all the external forces (F) acting on an object is zero

Question 30

Newtons third law

Answer 30

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

Question 31

Free body diagram

Answer 31

Shows all the external forces and moments acting on a body

Question 32

Mass

Answer 32

Quantity of matter

Question 33

Weight

Answer 33

Force of gravity acting on a body

Question 34

Density (p)

Answer 34

mass/volume

Question 35

Units for density

Answer 35

kg/m3

Question 36

If the mass of an object changes what will happen to volume and density

Answer 36

Volume changes proportionately, density remains constant

Question 37

Gravity

Answer 37

Acceleration due to gravitational attraction

Question 38

Weight

Answer 38

mass x acceleration due to gravity

Question 39

Gravity

Answer 39

9.81m/s2

Question 40

Centre of mass

Answer 40

A point where all the mass of the object can be assumed to act

Question 41

Can centre of mass lie outside the body?

Answer 41

Yes, when someone bends over, the centre of mass will move from the lower abdomen to lie just in front of the pelvis

Question 42

Centre of gravity

Answer 42

Point where the weight of a body can be assumed to act

Question 43

Pressure

Answer 43

Force exerted per unit area

Question 44

Pressure

Answer 44

force/area

Question 45

Unit for pressure

Answer 45

Pascals

Question 46

Moment of a force

Answer 46

Tendency of a force to produce a rotation about an axis, also called torque

Question 47

SI units of moments

Answer 47

Nm

Question 48

Moment equation

Answer 48

Moment= force x moment arm (M= fd)

Question 49

Lever

Answer 49

Consists of a rigid bar that pivots about a fulcrum

Question 50

What produces moments about the fulcrum

Answer 50

Effort force and resistance force

Question 51

Mechanical advantage

Answer 51

Effort arm longer than the resistance arm- easier to to overcome the resistance

Question 52

Mechanical disadvantage

Answer 52

Resistance arm longer than effort arm- resistance may be moved through relatively long distance

Question 53

Eq for mechanical advantage

Answer 53

effort arm/resistance arm

Question 54

Mechanical advantage >1

Answer 54

Effort force less than resistance force

Question 55

First class lever

Answer 55

Fulcrum located between effort and resistance e.g. see saw

Question 56

Second class lever

Answer 56

Resistance located between effort and fulcrum e.g. wheelbarrow

Question 57

Third class lever

Answer 57

Effort between resistance and fulcrum e.g. fishing rod