1.an engine develops 65kW over a period of 20minutes. The engine uses 5kg of petrol.
Calculate the following:-
A. The heat gegenerated
B. The power generated by the petrol
C. The efficiency Of the engine
2.A square steel plate with sides of 12cm long, is heated and the change in area is 1.723mm^2.determine the change in temperature
3.steam is generated in a boiler at pressure of 0.1MPa. Calculate the enthalpy required for 1kg of steam when the dryness factor is 0.96
4.a hydraulic press lifts a body of 2 tons. The diameter of the ram is twice the diameter of the plunger. Determine the effort force exerted by the plunger.
5. A force of 400N is exerted on the plunger of a hydraulic press. The diameter of the plunger is 400mm and the stroke length is 120cm. Calculate the following:
A.pressure exerted by the plunger.
B.volume delivered per stroke
C.work done after 10 pumping strokes of the plunger
1.
A. To calculate the heat generated, we can use the formula:
Heat = Power × Time
Given that the engine develops 65 kW of power over 20 minutes, we first need to convert 20 minutes into seconds:
Time = 20 minutes × 60 seconds/minute = 1200 seconds
Now we can calculate the heat generated:
Heat = 65 kW × 1200 seconds
B. The power generated by the petrol can be calculated using the formula:
Power = Energy / Time
Since we already have the power (65 kW) and the time (1200 seconds), we can use the same values to calculate the power.
C. The efficiency of the engine can be calculated using the formula:
Efficiency = (Useful output energy / Input energy) × 100%
To find the input energy, we need to calculate the energy used by the petrol. The energy can be calculated using the formula:
Energy = Power × Time
Given that the power is 65 kW and the time is 1200 seconds, we can use these values to calculate the energy.
Now we have the input energy and the useful output energy (which is the power developed by the engine). We can use these values to calculate the efficiency.
2.
To determine the change in temperature, we can use the formula:
Change in temperature = Change in area / Thermal expansion coefficient
Given that the square steel plate has sides of 12 cm long and the change in area is 1.723 mm², we need to convert the change in area to square centimeters:
Change in area = 1.723 mm² × (1 cm / 10 mm)²
Now we can use the formula to calculate the change in temperature. However, we need to know the thermal expansion coefficient of the steel plate, which is not provided in the question. Once we have the coefficient, we can substitute the values into the formula to find the change in temperature.
3.
To calculate the enthalpy required for 1 kg of steam, we need to use the specific enthalpy equation:
Enthalpy = Steam mass × (Specific enthalpy of vaporization × Dryness factor + Specific enthalpy of saturated water)
Given that the pressure of the steam is 0.1 MPa and the dryness factor is 0.96, we still need two values to apply in the equation: the specific enthalpy of vaporization and the specific enthalpy of saturated water. These values depend on the pressure and are typically provided in steam tables. We need to refer to the steam tables for the given pressure to obtain these values and then substitute them into the equation along with the given dryness factor to calculate the enthalpy.
4.
To determine the effort force exerted by the plunger, we need to use the principle of Pascal's law, which states that the pressure exerted in a fluid is transmitted equally in all directions. In this case, the pressure exerted by the plunger is equal to the pressure exerted by the ram.
Since the diameter of the ram is twice the diameter of the plunger, the area of the ram is four times the area of the plunger (since area is proportional to the square of the diameter).
Effort force = Force exerted by the ram / Area of the plunger
To find the effort force, we need to know the force exerted by the ram. The question does not provide this information, so we cannot determine the effort force without that information.
5.
A. To calculate the pressure exerted by the plunger, we can use the formula:
Pressure = Force / Area
Given that the force exerted on the plunger is 400 N and the diameter of the plunger is 400 mm, we need to convert the diameter to meters to calculate the area.
Area = (π/4) × (diameter)^2
Now we can use the formula to calculate the pressure.
B. To calculate the volume delivered per stroke, we can use the formula:
Volume = Area × Stroke length
Using the same area value we calculated in part A and the stroke length of 120 cm, we need to convert the stroke length to meters to calculate the volume.
Volume = Area × Stroke length
C. To calculate the work done after 10 pumping strokes of the plunger, we need to know the force exerted on the plunger, which is not provided in the question. Without that information, we cannot determine the work done.