Units

Question 1

nutritionist’s calories

Answer 1

Cal or kcal = 1000 cal

Question 2

1 cal = ? J

Answer 2

4.18 J

Question 3

The mass balance states

Answer 3

input = output

X + Y = 100

Question 4

Standardization

Answer 4

the process where the fat content of milk products is adjusted by the addition of cream or skim-milk.

input-output = accumulation

Question 5

steady state is achieved when

Answer 5

there is no accumulation of material, i.e. input = output

Question 6

batch operations, normally runs on

Answer 6

runs on a time basis (hourly)

100 = m+C

[m = mass of water removed; C = mass of concentrate produced]

Question 7

If 100 kg h-‘ of liquid containing 12% total solids is to be concentrated to produce a liquid containing 32% total solids, how much water is removed each hour?

Answer 7

100 = m+C

100 x 0.12= C x 0.32

It is assumed that the water leaving the evaporator contains no solid. Thus, C = 37.5kg , m = 62.5kg

Water needs to be removed at the rate of 62.5 kg h^-1

Question 8

accumulation

Answer 8

input +production-output = accumulation

Question 9

kgm^-3 is equivalent to

Answer 9

g l ^-1

Question 10

In a spontaneous change, heat (energy) is always transferred from _______ to ___________, until ___________ is achieved

Answer 10

from an object at a high temperature to one at a lower temperature
until thermal equilibrium is achieved

Question 11

• C = ? *F

* F = ? *C

Answer 11

• C = (*F- 32) x (5/9)

* F= (9/5) x *C +32

Question 12

absolute zero = 0 K

Answer 12

all molecular motion stops and the kinetic energy of the molecule becomes zero.

Question 13

K = ? *C

Answer 13

273. 15 + *C

Question 14

Carnot efficiency (CE)

Answer 14

a measure of the conversion of heat to work

CE = [(Heat 1 - Heat 2) / Heat 1] x 100

Question 15

Electric current (A)

Answer 15

a measure of the flow of electrons

unit = ampere (A)

Question 16

One ampere (1 A) is

Answer 16

flow of electrons which, when flowing down two long parallel conductors, of negligible cross-sectional area, placed 1 metre apart in a vacuum produces between the two wires a force of 2x 10^-7 N per metre of the length

Question 17

Luminous intensity unit

Answer 17

candela (cd)

Question 18

units of velocity

Answer 18

m s^-1

Question 19

surface area of a circle

Answer 19

r x r x pi

Question 20

surface area of a sphere

Answer 20

4 x pi x r x r = pi x Dx D

Question 21

1 m^2 = ? cm^2 = ? ft ^2

Answer 21

10^4 cm^2 = 10.76 ft ^2

Question 22

volumetric flow rate (Q)

units

Answer 22

Volume of fluid that passes through a given volume of space per unit of time

m^3 s^-1

Question 23

volume of a sphere

Answer 23

(4/3) x pi x r^3

Question 24

surface-area-to-volume ratio

Answer 24

[2 (r + h) ] / rh

Question 25

When heating an object, maximize the surface-area-to-volume ratio will

Answer 25

maximize the heat transfer rate and reduce the time required

Question 26

volume unit

Answer 26

m^3

Question 27

Density

Answer 27

mass/ volume kg m^-3

Question 28

Specific gravity

Answer 28

the mass of a substance divided by the mass of an equal volume of water has no units

Question 29

velocity

Answer 29

as distance covered divided by time taken to cover that distance. m s^-1

Question 30

average velocity (v)

Answer 30

volumetric flow rate Q (m^3 s^-1) / cross-sectional area A (m^2) m s^-1

Question 31

average velocity for a pipe or tube with diameter D

Answer 31

v = Q / pi x r^2

Question 32

Momentum units

Answer 32

kg m s^-1

Question 33

angular velocity

Answer 33

the velocity of an object moves in a circle of radius r angle subtended per unit time : (w) or (N) (w) rad s^-1 (N) rev s^-1 (w) = 2 pi N

Question 34

1 rad = ? * | 1 rev = ? rad

Answer 34

2 pi rad = 1 rev = 360* | 1 rad = 57.3*

Question 35

acceleration

Answer 35

the rate of change in velocity m s^-2

Question 36

terminal velocity

Answer 36

An object moving with a constant velocity has no acceleration

Question 37

gravity

Answer 37

9.81 m s^-2.

Question 38

Force units

Answer 38

masses, electric charges, magnetic poles, nuclear particles kg m s^-2 or N

Question 39

rheology

Answer 39

study of the deformation of objects under the influence of applied forces

Question 40

Newton’s second law of motion

Answer 40

when an object changes momentum, it is subjected to a force Fand that the magnitude of the force is proportional to the rate of change in momentum. force = rate of change in momentum

Question 41

centrifugal force

Answer 41

an outward force acting on the object, to balance the centripetal force and keep the object in the same relative position when moving round a circle a constant tip speed m r w^2 = [m v^2] / r

Question 42

centripetal force

Answer 42

an inward force apply to an object when it is moving round a circle at a constant tip speed. It is constantly changing its velocity because of its change in direction. centripetal force (N) = mass (kg) x centripetal acceleration (m s^-2) = m v^2 / r

Question 43

centripetal acceleration

Answer 43

centripetal acceleration (m s^-2) = v^2 / r or r w^2 ``` v = velocity (m/s) r = circular radius (m) ```

Question 44

Newton's third law

Answer 44

for every acting force there is an equal and opposite reaction force

Question 45

pressure

Answer 45

force / applied surface area kg m^-1 s^-2 or N m^-2 or Pa

Question 46

units of fluid density

Answer 46

kg m^-3

Question 47

absolute pressure

Answer 47

p = p g h ``` p = fluid density (kg m^-3) g = gravity (m s^-2) h = height of fluid head (m) ``` absolute pressure = gauges pressures + atmospheric pressure

Question 48

Positive pressure

Answer 48

gauges pressures > atmospheric pressure

Question 49

Vacuum pressure

Answer 49

gauges pressures < atmospheric pressure

Question 50

Shear stress.

Answer 50

The effect of a force acting parallel to a given area.

Question 51

Frequency:

Answer 51

v = n/t = s^-1 or Hz

Question 52

Period

Answer 52

T = t/n = 1 / v = 2pi/ w (s)

Question 53

Different velocity

Answer 53

- Force acts same line velocity - Force acts perpendicular to velocity - Force acts towards “o” and perpendicular to velocity - Forces is variable proportional to its distance to “o”

Question 54

Surface area of a cylinder

Answer 54

pi D L + 2 x pi r^2

Question 55

Work

Answer 55

a moving force through distance. It's energy kg m^-2 s or J

Question 56

Power

Answer 56

the rate of doing work. = work done/ time Watt = joule / second [ W or J s^-1]

Question 57

thermal conductivity

Answer 57

J s ^-1 m^-1 K^-1 or W m^-1 K^-1

Question 58

electricity bills unit

Answer 58

k W h

Question 59

pumping power

Answer 59

(pi - po) /pg ``` pi = inlet pressure po = outlet pressure p = fluid density (kg m^-3) g = gravity (m s^-2) ```

Question 60

theoretical power Po (W) delivered to the fluid

Answer 60

Po (W) = mass flow rate (kg s^-1) X head developed (m) x | acceleration due to gravity (m s^-2)

Question 61

molarity of solution

Answer 61

concentration / molecular weight

Question 62

concentration

Answer 62

mass of solid / total volume | or weight/ weight

Question 63

no of moles

Answer 63

mass / molecular weight