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Mechanical Engineering

A quantity of a certain perfect gas is compressed from an initial state of 0.085m3,1 bar to a final state of 0.034m3,3.9 bar. The specific heat at constant volume is 0.724kn/kgK,and the specific heat at constant pressure is 1.02kj/kgK.The observed temperature rise is 146K. Calculate,(a)The specific gas constant,R (b) the mass of gas present (d)the increase of initial energy of the gas.)

Mechanical Engineering

Design a three-mode temperature control system which inputs error in 0-4 V range. The output to final control element is 0-8 V. Given:

Kp = 2.4 % per %

Ki = 9 % (%/min)/ %

Kd = 0.7 % / (%/min)

Mechanical Engineering

A plate of a certain oil weighs 40kN. Calculate the specific mass, weight density and specific gravity of the oil.

Mechanical Engineering

A refrigerator works on the carnet cycle in temperature between -7°C and 27'C. It makes 500 kg of ice per hour at-5'C from water at 14'C. Find H.P required to drive the compressor and C.O.P. of the cycle. Take specific heat of ice as 2.1 KJ/Kg-k and latent heat as 336 kJ/Kg

Mechanical Engineering

An air refrigerator works between the pressure limit of 1bar and 5 bar. The temperature of the air entering the compressor and expansion cylinder is 10°C and 25°C. The expansion and compression follow the law of PV(13) C. Find the

following: 1) Theoretical COP of the refrigerating cycle

2) If the load on the refrigerating machine is 10 tons, then find the amount of air circulated per minute through the system assuming the actual COP is 50% of the theoretical COP

Assume L/D =1.5 and cp-1kJ/Kg °C and C=0.7

kJ/Kg °C for air

Mechanical Engineering

One of the wheels and leaf springs of an automobile, traveling over a rough road, is shown in Fig. For simplicity, all the wheels can be assumed to be identical and the system can be idealized as shown in Fig. The automobile has a mass of m1 = 1000 kg and the leaf springs have a total stiffness of k1 = 400 kN/m. The wheels and axles have a mass of m2 = 300 kg and the tires have a stiffness of k2− 500 kN/m. If the road surface varies sinusoidally with an amplitude of Y = 0.1 m and a period of l = 6 m, find the critical velocities of the automobile.

Mechanical Engineering

Find the natural frequencies of the system shown on the right, with m1=m, m2=2m, k1=k, and k2=2k. Determine the response of the system when k=1000 N/m, m=20 kg, and the initial values of the displacements of the masses m1 and m2 are l and -1 respectively.

Mechanical Engineering

A machine tool, having a mass of 1000 kg and a mass moment of inertia of J0 = 300 kg-m2 is supported on elastic supports, as shown in Figure given below. If the stiffness of the support is given by 3000 N/mm and 2000 N/mm, and the supports are located at 0.5 m and 0.8 m, find the natural frequencies.

Mechanical Engineering

The roofing design consists of a retractable roof where the roof is opened using a shaft that is

connected to a motor. The motor of 1hp transmits power to a rotor at 1200rev/min. Neglecting any

transmission losses, determine the maximum shear stress in the shaft due to the same applied

torque, if the maximum shear stress in the shaft is limited to 2MPa. The external diameter of the

shaft is 0.05m and a wall thickness of 0.005m What will be the resulting angle of twist of the shaft,

due to the applied torque, over a length of 2.5m, given that the rigidity modulus, G=70GPa.

(1hp=745.7W)

Mechanical Engineering

The 96 prismatic lithium-ion battery cells were manufactured in Korea and the Scottish firm Axeon assembled them into a 1411-pound, 338-volt pack that provides a 71-kWh energy capacity and a claimed 1D miles of range [Note: replace D with your ID’s last two digits].

(d) Using the charge capacity of the battery derived in c, use dimensional analysis techniques to:

1. Determine the dimensions of Q using only mass, length and time.

2. Determine the equation that governs charging time of the battery.

3. If the charging current is 10 A. Find charging time assuming the values provided in c are valid values for part d.