# Machine Dynamics Questions and Answers – Dynamometer

This set of Machine Dynamics Multiple Choice Questions & Answers (MCQs) focuses on “Dynamometer”.

1. Which of the following is a characteristic feature of a dynamometer?
a) It can measure torque
b) It can measure frictional resistance
c) It can measure the balancing force
d) It can act as a speedometer

Explanation: Dynamometer is a device that acts as a brake but in addition to this, it can also measure frictional resistance and can measure the power of the engine.

2. Prony brake dynamometer is an absorption dynamometer.
a) True
b) False

Explanation: Pronybrake dynamometer absorbs all the energy produced by the engine through frictional resistances hence it is an absorption dynamometer.

3. In which of the following dynamometers does the entire energy or power produced by the engine is absorbed by the friction resistances of the brake?
a) Prony brake dynamometer
b) Torsional dynamometer
c) Epicyclic train dynamometer
d) Belt transmission dynamometer

Explanation: Prony brake dynamometer is an absorption dynamometer, in absorption dynamometers the entire energy or power produced by the engine is absorbed by the friction resistances of the brake and is transformed into heat.

4. In which of the following dynamometers does the energy produced by the engine is used for doing work?
a) Prony brake dynamometer
b) Rope brake dynamometer
c) Absorption dynamometer
d) Epicyclic train dynamometer

Explanation: An epicyclic train dynamometer is an example of transmission dynamometer. In these types of dynamometers the energy is not wasted in friction but is used for doing work.

5. Flywheel diameter 1.2 m; diameter of the rope 12.5 mm; engine speed 200 r.p.m.; dead load on the brake 600 N; spring balance reading 150 N. Using this data, calculate the brake power of the engine in kW.
a) 5.715
b) 5.525
c) 6.125
d)5.625

Explanation: The brake power of an engine is given by the relation:
B.P = [(W-S)π (D+d)N]/60
= 5715 W.
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6. Flywheel diameter 1.2 m; diameter of the rope 12.5 mm; engine speed 400 r.p.m.; dead load on the brake 600 N; spring balance reading 150 N. Using this data, calculate the brake power of the engine in kW.
a) 12.82
b) 11.43
c) 13.64
d) 10.22

Explanation: The brake power of an engine is given by the relation:
B.P = [(W-S)π (D+d)N]/60
= 11430 W.

7. For a rope brake dynamometer, the flywheel is cooled with soapy water because________
a) Energy is absorbed by the dynamometer
b) Energy is used to do work
c) Energy is provided by the motor
d) Energy supplied is more

Explanation: A rope brake dynamometer is an example of absorption dynamometer, in absorption dynamometers the entire energy or power produced by the engine is absorbed by the friction resistances of the brake and is transformed into heat. Hence to overcome this soapy water is used.

8. Belt transmission dynamometer is an absorption dynamometer.
a) True
b) False

Explanation: Belt transmission dynamometer is a transmission dynamometer as a result the energy is not wasted in friction but is used for doing work.

9. For which of the following dynamometers the driving torque on the shaft is not uniform and it is subjected to severe oscillations?
a) Pony brake
b) Band brake
c) Belt transmission
d) Epicyclic train

Explanation: For a pony brake dynamometer, When the driving torque on the shaft is not uniform, it is subjected to severe oscillations.

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