B is the answer I believe so
Question
Determine the average water exit velocity
Answer:
53.05 m/s
Explanation:
Given information
Volume flow rate, 
Diameter d= 8cm= 0.08 m
Assumptions
- The flow is jet flow hence momentum-flux correction factor is unity
- Gravitational force is not considered
- The flow is steady, frictionless and incompressible
- Water is discharged to the atmosphere hence pressure is ignored
We know that Q=AV and making v the subject then
where V is the exit velocity and A is area
Area,
where d is the diameter
By substitution

To convert v to m/s from m/s, we simply divide it by 60 hence

Answer:
(a) the velocity ratio of the machine (V.R) = 1
(b) The mechanical advantage of the machine (M.A) = 0.833
(c) The efficiency of the machine (E) = 83.3 %
Explanation:
Given;
load lifted by the pulley, L = 400 N
effort applied in lifting the, E = 480 N
distance moved by the effort, d = 5 m
(a) the velocity ratio of the machine (V.R);
since the effort applied moved downwards through a distance of d, the load will also move upwards through an equal distance 'd'.
V.R = distance moved by effort / distance moved by the load
V.R = 5/5 = 1
(b) The mechanical advantage of the machine (M.A);
M.A = L/E
M.A = 400 / 480
M.A = 0.833
(c) The efficiency of the machine (E);

Answer:
Amount of air left in the cylinder=m
=0.357 Kg
The amount of heat transfer=Q=0
Explanation:
Given
Initial pressure=P1=300 KPa
Initial volume=V1=0.2
Initial temperature=T
=20 C
Final Volume=
=0.1 
Using gas equation

m1==(300*0.2)/(.287*293)
m1=0.714 Kg
Similarly
m2=(P2*V2)/R*T2
m2=(300*0.1)/(0.287*293)
m2=0.357 Kg
Now calculate mass of air left,where me is the mass of air left.
me=m2-m1
me=0.715-0.357
mass of air left=me=0.357 Kg
To find heat transfer we need to apply energy balance equation.

Where me=m1-m2
And as the temperature remains constant,hence the enthalpy also remains constant.
h1=h2=he=h
Q=(me-(m1-m2))*h
me=m1-me
Thus heat transfer=Q=0
Answer:
The total number of people whom have made machines is not a recorded figure? Need to be more specific :/
Explanation:
Sorry not very helpful, your question is REALLY broad