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

1. What is the permissible limit of noise while using machinery for an eight-hour work in the field?

a) 90 dB

b) 100 dB

c) 105 dB

d) 110 dB

View Answer

Explanation: An operator working in a farm may have an exposure to noise since farm machinery can make a high undesirable sound. As per data if an operator is working for 8 hours it is permissible to listen up to 90 dB and if the noise level increases the working (exposure to noise) hour should be reduced.

2. What is the maximum sound pressure level theoretically in the earth atmosphere?

a) 194 dB

b) 196 dB

c) 200 dB

d) 199 dB

View Answer

Explanation: The maximum sound pressure level in the atmosphere is 194 dB which is transmitted through the atmosphere’s pressure. The atmospheric pressure is 1 bar = 10

^{5}N/m

^{2}

SPL = 20 log P

_{max}/P

_{0}

= 20 log (10

^{5})/(2*10

^{-5})

= 193.979 dB

3. What is a sound pressure level?

a) Expression of sound pressure

b) Expression of atmospheric pressure

c) Expression of sound velocity

d) Expression of air velocity

View Answer

Explanation: Sound pressure level is the expression of sound pressure on a logarithmic scale. It is measured in the unit of decibel (dB). It is calculated with a reference sound pressure.

4. How to calculate the sound pressure level?

a) SPL = 20 log P/P_{0}

b) SPL = 20 log P_{0}/P

c) SPL = 20 log P * P_{0}

d) SPL = 20 log P

View Answer

Explanation: The sound pressure level is defined as the 20 log of the ration of RMS sound pressure to the reference sound pressure P

_{0}= 2 * 10

^{-5}N/m

^{2}, the threshold of hearing of sound.

5. What is the root mean square sound pressure?

a) RMS pressure = √(Mean of the square of pressure)

b) RMS pressure = √(Mean of pressure)

c) RMS pressure = p^{2}

d) RMS pressure = Mean of the cube root of pressure

View Answer

Explanation: The root mean square sound pressure is used to characterize the sound wave. The mean of the square of the pressure of the sound waves in an interval and then square root has taken over the mean value to obtain RMS sound pressure.

6. Find the sound pressure level of a sound at the tractor cab having RMS sound pressure as 0.5 Pa.

a) 107 dB

b) 110 dB

c) 120 dB

d) 100 dB

View Answer

Explanation: SPL = 20 log P/P

_{0}

= 20 log 10 (0.5 / 2 * 10

^{-5})

= 107 dB

Where P

_{0}is the reference sound pressure 2 * 10

^{-5}N/m

^{2}

7. The doubling of the sound pressure will increase the sound pressure level to 6 dB.

a) False

b) True

View Answer

Explanation: If the sound pressure is doubled, it will increase the sound pressure level up to 6 dB from its normal (initial) level. The sound pressure level depends upon the energy liberated by the acoustic source and so it is being a rule of thumb.

8. Noise will increase the heartbeat and blood pressure of the operator.

a) True

b) False

View Answer

Explanation: The prolonged exposure to high noise will cause significant effects in the operator body. It may cause ear ailments, increase pulse rate and increase blood pressure. So, the operator should always wear earplug to work in a high noisy field.

9. Find the sound pressure level if the sound pressure is doubled.

a) 8 dB

b) 6 dB

c) 9 dB

d) 10 dB

View Answer

Explanation: SPL

_{1}= 20 log P

_{1}/P

_{0}

If sound pressure is doubled SPL

_{2}= 20 log (2P

_{1}/P

_{0})

SPL

_{2}– SPL

_{1}= 20 log (2P

_{1}/P

_{0}) – 20 log P

_{1}/P

_{0}

= 20 log (2 P

_{1}) – 20 log P

_{0}– 20 log P

_{1}+ 20 log P

_{0}

= 20 log 2 + 20 log P

_{1}– 20 log P

_{1}

= 20 * 0.30102

= 6.0205 dB

10. Find the Root mean square sound pressure as the sound pressure level is 75 dB.

a) 0.1124 Pa

b) 1.001 Pa

c) 1.250 Pa

d) 1.503 Pa

View Answer

Explanation: SPL = 20 log P/P

_{0}

75 = 20 log (P/(2 * 10

^{-5}))

75/20 = log (P/(2 * 10

^{-5}))

3.75 = log P – log (2 * 10

^{-5})

3.75 = log P – log 2 – log 10

^{-5}

3.75 = log P – log 2 + 5 log 10

3.75 = log P – 0.30102 + 5

3.75 = log P + 4.699

Log

_{10}P = -0.949

P = 10

^{(-0.949)}= 0.1124 Pa

11. How the loudest noise is produced from the tractor?

a) Combustion, gear movements

b) Tractor horn

c) Steering

d) Braking

View Answer

Explanation: The tractor can produce loud noises due to reciprocating parts. From combustion, piston slap, gear movements, exhaust process noises are produced which affect the efficiency of the operator.

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

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