At the end of compression stroke the Air is the Combustion space of a certain spark ignition engine develops a space of 50cm³. The pressure is 10³ N/m² (bar) and the temperature is 170°C. Calculate the mass & fuel ratio; m=14.7/1! Take R for air = 287 J/K. Calculate the barometric pressure to be.

$$m_{air} = \frac{PV}{R_{air}T}$$ $$m_{air} = \frac{(13 \times 10^5 \text{ Pa}) \times (50 \times 10^{-6} \text{ m}^3)}{(287 \text{ J/kg K}) \times (443.15 \text{ K})}$$ $$m_{air} = \frac{65}{127100.055}$$ $$m_{air} \approx 0.0005114 \text{ kg}$$

$$\text{AFR} = \frac{m_{air}}{m_{fuel}}$$ $$m_{fuel} = \frac{m_{air}}{\text{AFR}}$$ $$m_{fuel} = \frac{0.0005114 \text{ kg}}{14.7}$$ $$m_{fuel} \approx 0.00003479 \text{ kg}$$

The mass of fuel to be injected is $\boxed{\text{0.00003479 kg}}$.

Q6:
When safety is not observed in an Automobile Workshop, the following can result:

• a) Distracted mindset on the job: This can lead to errors, accidents, and injuries due to lack of focus on the task at hand, especially when operating machinery or handling hazardous materials.
• b) Work when you are overtired: Fatigue impairs judgment and reaction time, significantly increasing the risk of accidents, mistakes, and serious injuries.
• c) Wear unclean overall: Unclean overalls, especially if soaked with oil, grease, or flammable liquids, pose a fire hazard and can cause skin irritation or infections.
• d) Not wearing safety boot: This exposes feet to hazards like falling objects, crushing injuries, punctures from sharp objects, and electrical shocks.
• e) Wear jewelry (ring, neck jewelry, neck chain): Jewelry can get caught in moving machinery, leading to severe injuries like degloving or amputation. It can also conduct electricity, causing electrical shocks or burns.

Q7:

a) Three categories of fire classifications in a workshop are: * Class A: Fires involving ordinary combustible materials such as wood, paper, cloth, rubber, and plastics. * Class B: Fires involving flammable liquids (e.g., gasoline, oil, paint) and flammable gases (e.g., propane, natural gas). * Class C: Fires involving energized electrical equipment.

b) Five important factors to be considered for preventing most explosions and fire spreading in a workshop are: * Proper Storage of Flammables: Store flammable liquids and gases in approved, clearly labeled containers and cabinets, away from ignition sources. * Good Housekeeping: Maintain a clean and organized workspace, regularly removing combustible waste, oily rags, and clutter that could fuel a fire. * Control of Ignition Sources: Eliminate or control sources of ignition such as open flames, sparks from welding or grinding, hot surfaces, and faulty electrical equipment. * Adequate Ventilation: Ensure proper ventilation to prevent the buildup of flammable vapors or dust, which can lead to explosions. * Emergency Preparedness and Training: Have functional fire extinguishers, alarms, and emergency exits. Regularly train staff on fire prevention, evacuation procedures, and the correct use of fire-fighting equipment.