Powerplants

Question 1

What is the definition and formula of “force”?

Answer 1

Force=Mass x Acceleration / F=M x A

Measured in units of newtons or pounds force.

Question 2

What is the definition and formula of “work done”?

Answer 2

Work Done=Force x Distance / W=F x D

Measured in units of Joules or Foot pounds

Question 3

What is the definition of ‘’Power” and what is the units used?

Answer 3

Work done per unit time.

Measured in joules/second (watts)
Or
Foot pounds per minute, expressed in horsepower (HP)
1HP=33,000 foot pounds/minute

Question 4

What is Newton’s first law of motion (The Inertia Law)

Answer 4

A body will remain at rest or in uniform motion in a straight line unless acted on by an external force.

Question 5

What is Newton’s second law of motion (The Momentum Law).

Answer 5

The acceleration of a body from a state of rest or uniform motion in a straight line, is PROPORTIONAL to the applied force and INVERSELY PROPORTIONAL to the mass of the body.

Question 6

What is the acceleration formula?

Answer 6

Acceleration= Velocity(final) - Velocity(initial) / Time(t) in m/s

Question 7

What is Newton’s third law of motion (The Reaction Law)

Answer 7

For every action there is an equal and opposite reaction.

Question 8

What is the first law of thermodynamics?

Answer 8

Heat and mechanical energy are mutually convertible. The rate of exchange is constant and can be measured.

Question 9

What is the second law of thermodynamics?

Answer 9

Heat cannot be transferred from a region at a lower temperature to one at a higher temperature without the expenditure of energy from an external source.

Question 10

Bernoulli’s Theorem - What are the three forms of energy?

Answer 10

1) The energy due to it’s height or position (the potential energy).
2) The energy due to it’s pressure.
3) The energy due to it’s movement (the kinetic energy)

note: In the streamline flow of an ideal fluid the sum of all these is constant.

Question 11

What is the definition of the ‘’Continuity Equation’’?

Answer 11

For a flow of air to remain streamlined, the mass flow passing a particular point in a set period of time must remain constant.

Question 12

What is the formula for Bernoulli’s Continuity Equation (Constant Mass Flow)?

Answer 12

Mass = Area (A) 
         x Density (D)
         x   Velocity (V) 
         = a constant (K)

Question 13

What happens at the ‘’convergent duct’’ in a Venturi tube?

Answer 13

Velocity Increases
Pressure Decreases
Temperature Decrease

Question 14

What happens at the “narrowest point (throat)’’ in a Venturi tube?

Answer 14

Maximum Velocity
Minimum Pressure
Minimum Temperature

Question 15

What happens at the “divergent duct” in a Venturi tube?

Answer 15

Velocity decreases
Pressure increases
Temperature increases

Question 16

How is a Venturi useful in a carburettor?

Answer 16

At the narrow section of the Venturi, fuel can be sucked into the throat of the carburettor as the pressure will have dropped, causing a vacuum effect.

Question 17

What is the definition for Boyle’s Law?

Answer 17

If a fixed gas is held at temperature, the volume of that gas is inversely proportional to it’s absolute pressure.

Question 18

What is the formula for Boyle’s Law?

Answer 18

Pressure (P) x Volume (V) = a constant (K)

Question 19

What’s is the definition of ‘’Charles’s Law /Gay-Lussacs Law’’?

Answer 19

If a fixed mass of gas is held at a constant pressure, it’s volume is directly proportional to it’s absolute temperature.

Question 20

What is the formula for Charles’s Law /Gay-Lussacs Law’’?

Answer 20

Volume (V) / Temperature (T) = constant (K)

Question 21

What is the ‘’Combined Gas Law (Ideal gas Law)’’ ?

Answer 21

By combining Boyle’s Law and Charles’s law’s together we can get a combined gas law which represents the relationship between the volume, pressure and temperature of a fixed mass of gas.

Question 22

What is the formula for the ‘’Combined Gas Law (Ideal gas Law)’’ ?

Answer 22

Pressure (P) x Volume (V) / Absolute Temperature (T) = a constant (K)

P1 x V1 / T1 = P2 x V2 / T2

Question 23

Describe the induction stroke in a theoretical internal combustion engine.

Answer 23

The piston moves down, volume increases, pressure reduces, temperature falls.

Question 24

Describe the compression stroke in a theoretical internal combustion engine.

Answer 24

The piston rises, volume reduces, pressure increases, temperature rises.

Question 25

Describe the power stroke in a theoretical internal combustion engine.

Answer 25

Mixture ignites, temperature and pressure rise initially, but fall subsequently as volume increases.

Question 26

What is the typical compression ratio of a 4 stoke petrol/gasoline engine?

Answer 26

8:1 to 10 : 1

Question 27

What is the the typical compression ratios for a Diesel engine?

Answer 27

14:1 and up to 28:1