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9.1 Calculate the: 9.1.1 Rotation frequency of the driver pulley in r/min (4) 9.1.2 Power transmitted in this system (4) 9.2 FIGURE 9.2 shows a gear-drive system - NSC Mechanical Technology Welding and Metalwork - Question 9 - 2016 - Paper 1

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Question 9

9.1-Calculate-the:--9.1.1-Rotation-frequency-of-the-driver-pulley-in-r/min-(4)--9.1.2-Power-transmitted-in-this-system-(4)--9.2-FIGURE-9.2-shows-a-gear-drive-system-NSC Mechanical Technology Welding and Metalwork-Question 9-2016-Paper 1.png

9.1 Calculate the: 9.1.1 Rotation frequency of the driver pulley in r/min (4) 9.1.2 Power transmitted in this system (4) 9.2 FIGURE 9.2 shows a gear-drive system.... show full transcript

Worked Solution & Example Answer:9.1 Calculate the: 9.1.1 Rotation frequency of the driver pulley in r/min (4) 9.1.2 Power transmitted in this system (4) 9.2 FIGURE 9.2 shows a gear-drive system - NSC Mechanical Technology Welding and Metalwork - Question 9 - 2016 - Paper 1

Step 1

9.1.1 Rotation frequency of the driver pulley in r/min

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Answer

To calculate the rotation frequency of the driver pulley, we can use the formula:

n=VπDn = \frac{V}{\pi D}

Where:

  • VV is the belt speed (36 m/s)
  • DD is the diameter of the driver pulley (0.23 m)

Substituting the values:

n=36π×0.2349.82 r/sn = \frac{36}{\pi \times 0.23} \approx 49.82~\text{r/s}

Converting to r/min:

n49.82×602989.35 r/minn \approx 49.82 \times 60 \approx 2989.35~\text{r/min}

Step 2

9.1.2 Power transmitted in this system

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Answer

To calculate the power transmitted, we can use the formula:

P=(TtTs)×VP = (T_t - T_s) \times V

Where:

  • TtT_t is the tension in the tight side (350 N)
  • TsT_s is the tension in the slack side (140 N)
  • VV is the belt speed (36 m/s)

Based on the tension ratio, we have:

Ts=Tt2.5=3502.5=140NT_s = \frac{T_t}{2.5} = \frac{350}{2.5} = 140 N

Now substituting into the power formula:

P=(350140)×36=7560 W or 7.56 kWP = (350 - 140) \times 36 = 7560~\text{W}~\text{or}~7.56~\text{kW}

Step 3

9.2.1 Rotation frequency of the input shaft on the electric motor if the output shaft needs to rotate at 160 r/min

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Answer

Given the gear system, the rotation frequencies are linked through gear ratios:

Let:

  • NOUTPUT=160 r/minN_{OUTPUT} = 160~\text{r/min}
  • NINPUTN_{INPUT} be the unknown frequency for the motor shaft.

Using the gear ratio relationships:

NINPUT=TATB×TCTD×TETF×NOUTPUTN_{INPUT} = \frac{T_A}{T_B} \times \frac{T_C}{T_D} \times \frac{T_E}{T_F} \times N_{OUTPUT}

Substituting the teeth counts:

NINPUT=1836×1646×4060×160N_{INPUT} = \frac{18}{36} \times \frac{16}{46} \times \frac{40}{60} \times 160

Calculating:

NINPUT=0.5imes1646imes4060imes1601380 r/minN_{INPUT} = 0.5 imes \frac{16}{46} imes \frac{40}{60} imes 160 \approx 1380~\text{r/min}

Step 4

9.2.2 Velocity ratio between the input shaft and output shaft

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Answer

To find the velocity ratio (VR), we use:

VR=NINPUTNOUTPUTVR = \frac{N_{INPUT}}{N_{OUTPUT}}

Using the previously calculated rotation frequencies:

VR=1380160=8.6258.63VR = \frac{1380}{160} = 8.625\approx 8.63

Step 5

9.3.1 Fluid pressure in the hydraulic system when in equilibrium

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Answer

To calculate the fluid pressure, we first find the area of piston A:

AA=πD24=π(0.04)241.2566×103 m2A_A = \frac{\pi D^2}{4} = \frac{\pi (0.04)^2}{4} \approx 1.2566 \times 10^{-3}~m^2

Now apply the pressure formula:

PA=FAAA=2751.2566×103218,884 Pa=218.84 kPaP_A = \frac{F_A}{A_A} = \frac{275}{1.2566 \times 10^{-3}} \approx 218,884~\text{Pa} = 218.84~\text{kPa}

Step 6

9.3.2 Load in kilogram that can be lifted by piston B if a force of 275 N is exerted upon piston A

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Answer

For piston B, first calculate its area:

AB=π(0.075)244.42×103 m2A_B = \frac{\pi (0.075)^2}{4} \approx 4.42 \times 10^{-3}~m^2

To find the force on piston B:

FB=PB×AB=218,884×4.42×103967.32 NF_B = P_B \times A_B = 218,884 \times 4.42 \times 10^{-3} \approx 967.32~N

Now converting this to mass:

Mass=FBg=967.329.8196.73 kg\text{Mass} = \frac{F_B}{g} = \frac{967.32}{9.81} \approx 96.73~kg

Step 7

9.4 What is the purpose of traction control in a vehicle?

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Answer

The purpose of traction control is to prevent the wheels from spinning during acceleration. This system helps maintain optimal grip between the tires and the road surface, enhancing vehicle stability, performance, and safety in various driving conditions.

Step 8

9.5 Explain the meaning of the term passive safety feature.

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Answer

A passive safety feature is designed to protect occupants in the event of an accident without requiring any action from the driver or passengers. Airbags are a prime example, as they automatically deploy to cushion and protect those inside the vehicle during a collision.

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