This set of Farm Tractor Multiple Choice Questions & Answers (MCQs) focuses on “Operator Exposure to Vibration and Control”.

1. What is meant by frequency in a tractor operation?

a) f = 1/T

b) f = T

c) f = 1 – T

d) f = T – 1

View Answer

Explanation: Frequency is the number of occurrences/cycles in a specific period of time. It is a measure of vibration. It is measured in Hertz (Hz). F = 1/T, where T is the duration for the completion of one cycle. Here it is the frequency of the tractor parts like operator seat etc.

2. Prolonged exposure to vibrations causes fatigue to the operator.

a) False

b) True

View Answer

Explanation: The vibrations caused by the tractor will increase the strain in the operator and so it will cause fatigue to the operator. Tractors should be designed to have minimum vibrations.

3. Operator seat of a tractor is subjected to which type of vibration?

a) Forced vibration

b) Free vibration

c) Damped vibration

d) Applied vibration

View Answer

Explanation: Tractor operator seat is subjected to forced vibration as it receives vibrational force from the chassis – an external source. Vibrations with higher frequency are not suitable for the operator.

4. Calculate the tractor chassis frequency in rad/s of a tractor having frequency 25 Hz.

a) 157 rad/s

b) 155 rad/s

c) 146 rad/s

d) 156 rad/s

View Answer

Explanation: ω

_{t}= 2πf

Where ω

_{t}is the tractor chassis frequency in rad/s

ω

_{t}= 2 * π * 25

= 157.1 rad/s

5. Find the frequency in hertz if the number of occurrences is 1800 in a period of one minute.

a) 30 Hz

b) 29 Hz

c) 31 Hz

d) 32 HZ

View Answer

Explanation: f = 1/T (where T is in seconds)

Where 1 is the number of occurrence in the formula similarly the number of occurrences given is 1800.

= 1800/60

= 30 Hz

6. Find the damped frequency of a tractor seat given the natural frequency is 20 Hz and the damping ratio is 0.5.

a) 15 Hz

b) 16 Hz

c) 17 Hz

d) 18 Hz

View Answer

Explanation: ω

_{d}= ω

_{n}√(1-ζ

^{2})

Where ω

_{d}– damped frequency, ζ – damping ratio and ω

_{n}– natural frequency

= 20 √(1-0.5

^{2})

= 17.32

7. Find the damping ratio given the seat suspension damping rate is 500 N/ms, the mass of the tractor seat + operator is 80 kg and the natural frequency is 20 rad/s.

a) 0.10

b) 0.15

c) 0.18

d) 0.20

View Answer

Explanation: Damping ratio = C/C

_{c}

Where C – seat suspension damping rate

C

_{c}– Critical damping rate

C

_{c}= 2 M ω

_{n}

Where M – the mass of the tractor seat and operator, ω

_{n}– undamped natural frequency

ζ = 500 / 2 * 80 * 20 = 0.15

8. Damping ratio has no unit.

a) True

b) False

View Answer

Explanation: Damping ratio has no unit as it measures the damping in the system. Here the damping refers to the reduction in the vibration/oscillation. It is also referred to as the damping factor.

9. Find the vibration acceleration level given RMS value of vibration acceleration is 2 m/s^{2}.

a) 7 dB

b) 6 dB

c) 8 dB

d) 9 dB

View Answer

Explanation: Vibration acceleration level = 20 log

_{10}(V

_{RMS}/ V

_{0})

Where V

_{0}is the reference vibration acceleration (1 m/s

^{2})

= 20 log

_{10}(2/1) = 6.02 dB

10. Find the RMS value of vibration acceleration given that the peak vibration acceleration is 10 m/s^{2}.

a) 7.07 m/s^{2}

b) 7.5 m/s^{2}

c) 8.07 m/s^{2}

d) 9.07 m/s^{2}

View Answer

Explanation: V

_{RMS}= (1/√2) * (V

_{peak})

= (1/√2) * (10)

= 7.07 m/s

^{2}

Where V

_{peak}– peak vibration acceleration, V

_{RMS}– root mean square (RMS) value of vibration acceleration.

**Sanfoundry Global Education & Learning Series – Farm Tractor.**

To practice all areas of Farm Tractor, __here is complete set of Multiple Choice Questions and Answers__.

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