Engineering Questions with Answers - Multiple Choice Questions

# Machine Dynamics MCQ – Turning Moment Diagram for a Four Stroke Cycle Internal Combustion Engine

1 - Question

Which of the following process is not the part of working of a 4 stroke I.C Engine?
a) Compression
b) Suction
c) Exhaust
d) Turbine flow

Explanation: 4 stroke IC engine works through suction compression working or power stroke and then exhaust. It does not use turbine hence no turbine flow is used.

2 - Question

4-stroke engine has one power stroke per 2 revolutions hence turning moment diagram is uniform.
a) True
b) False

Explanation: One power stroke per 2 revolutions of crank shaft hence its turning moment is not uniform so heavier flywheel is needed.

3 - Question

Work produced by the 4-stroke engine is less because _______
a) One power stroke per 2 revolutions
b) One power stroke per revolution
c) One power stroke per 4 revolution
d) Four power stroke per revolution

Explanation: One power stroke per 2 revolutions of crank shaft hence its turning moment is not uniform so heavier flywheel is needed and hence results in less power generation.

4 - Question

A negative loop is formed in the turning moment diagram because the pressure inside the cylinder is _______ than the atmospheric pressure.
a) Equal
b) More
c) Less
d) No pressure inside

Explanation: A negative loop is formed in the turning moment diagram of a 4 stroke IC engine because during suction the pressure inside the engine is reduced due to intake and has a lower value than the atmospheric pressure.

5 - Question

When the work is done on the gases, which of the following effect is observed on the turning moment diagram?
a) Formation of negative loop
b) Formation of positive loop
c) Formation of an infinite loop
d) Formation of no loop

Explanation: When the work is done on the gases, the pressure inside the cylinder decreases and has a value lower than the atmospheric pressure, as a result a negative loop is formed.

6 - Question

When the work is by on the gases, which of the following effect is observed on the turning moment diagram?
a) Formation of negative loop
b) Formation of positive loop
c) Formation of an infinite loop
d) Formation of no loop

Explanation: When the work is done by the gases, the pressure inside the cylinder increases and has a value higher than the atmospheric pressure, as a result a positive loop is formed.

7 - Question

Compression stroke results in ________
a) Formation of negative loop
b) Formation of positive loop
c) Formation of an infinite loop
d) Formation of no loop

Explanation: During compression stroke, the work is done on the gases, the pressure inside the cylinder decreases and has a value lower than the atmospheric pressure, as a result a negative loop is formed.

8 - Question

4 strokes engine have a lower thermal efficiency than 2 stroke engine.
a) True
b) False

Explanation: 4-stroke IC engines despite having low power output per cycle have a higher thermal efficiency than a 2 stroke cycle because in 2 stroke engines, the fuel escapes with the exhaust.

9 - Question

While drawing the turning moment diagram, which of the forces in not taken into account?
a) Inertia force
b) Force on connecting rod
c) Force on crank
d) Coriolis force

Explanation: When a turning moment diagram is drawn, it takes into account all the forces inertia, connecting rod and crank however there is no coriolis force acting in the engine thus it is not taken into account.

10 - Question

In the given turning moment diagram, the process X is known as ______

a) Suction
b) Compression
c) Power
d) Exhaust