Mechanical Engineering Answers

A mass of air has an initial pressure of 1.3 MN/m ² , volume 0.014 and temperature 135 ⁰C. It is expanded until its final pressure is 275 kN/m ² and its volume becomes 0.056 m³ . Determine

a)The mass of air

b)The final temperature

Take R = 0.287 kJ/kg k

A mass of gas has an initial pressure of 1 bar and a temperature of 20 ⁰C. The temperature of the gas is now increased to 550 ⁰C while the volume remains constant. Determine the final pressure of the gas.

A quantity of gas has an initial volume of 0.06 m³ and a temperature of 15 ⁰C. It is expanded to a volume of O. 12 m³ while the pressure remains constant. Determine the final temperature of the gas.

A quantity of gas has an initial pressure of 140 kN/m² and volume 0.14 m³ It then compressed to a pressure of 700 kN/m² while the temperature remains constant Determine the final volume of the gas.

An open belt drive consists of two pulleys which are 5 m apart. The diameters of the larger pulley and smaller pulley are 2 m and 1 m respectively. The allowable maximum tension of the belt is 4 kN. The coefficient of friction between the belt and the pulley is 0.4 and the mass of the belt is 2kg/m length. Calculate:

3.1. The torque on the shafts when the larger pulley rotates at 300 RPM. (7)

3.2. The power transmitted. (3)

3.3. The speed in RPM at which maximum power can be transmitted. (5) 3.4. The maximum power that can be transmitted. (3)

A power of 4.5 kW must be transmitted from a pulley of an effective diameter of 0.25 m. The pulley is running at 1200 RPM. The angle of contact is 160° and the groove angle is 40°. The coefficient of friction is 0.2. If the allowable tension in each belt is 100 N, calculate the number of V-belts that will be required to transmit the power.

A vehicle has a wheel base of 3 m with a centre of gravity 0.8 m above ground level and 1.8 m in front of the rear axle. The coefficient of friction between the wheels and the road is 0.5. The vehicle is traveling horizontally at 90 km/h. Calculate the shortest distance at which the vehicle can be brought to a standstill by means of: 1.1. The brakes on the rear wheels only (14)

1.2. The brakes on both front and rear wheels. 

The velocity field of a flow is given 2 2 V x ti y t x t j m s = + −+ 2 4 ( 1) 2 / ⎡ ⎤ ⎣ ⎦ K JK , where x and y are in meters and t is seconds. For fluid particles on the x axis, determine the speed and direction of flow.