Mechanical Engineering Answers

A hole (diameter 5+-0,1 mm) is drilled into a cube (edge 20+- 0,2 mm). Calculate the volume of the body and its cumulative error.

A piston cylinder contains gas initially at 3500 kPa with a volume of 0.03 cubic meter. The gas is compressed during a process where pV raise to 1.25 = C to a pressure of 8500 kPa. The heat transfer from the gas is 2.5 kJ. Determine the change in internal energy, neglecting changes in kinetic and potential energies. Graph a PV and TS Plane.

A 2.5m long steel towing bar of solid circular section diameter 50mm is expected to carry a maximum load of 300kN. The factore of safety is 4; and for the steel the UTS is 540Mnm*-2 (to the power of -2) and the modulas of elasticity is 200 GNm*-2.

Calculate the actual towing capacity of the bar and state whether the proposed limit is acceptable.

determine the amount of heat energy needed to change 250g of ice at -10c into superheated stream at 130c given that the latent heat of fusion of ice is 335kj/kg the specific heat capacity of ice is 2.14kj/kg the specific heat capacity of water is 4.2kj/kg the specific heat capacity of stream is 2.01kj/kgk the latent heat of vaporisation of water is 2.26mj/kg

Task 2
A heat exchanger produces dry steam at 100 C from feed water at 30C at a rate of 1.5 kgs^-1. The heat exchanger receives heat energy at a rate of 600 kW from the fuel used. The specific heat capacity of water is 4187 Jkg^-1K^-1 and its specific latent heat of vaporisation is 2257 Jkg^-1.
A) determine the heat energy received per kilogram of steam produced.
B)determine the output power of the heat exchanger and its thermal efficiency.

A vehicle of mass 1010kg accelerates uniformly from rest to a velocity of 62 kmh−1 in 10 s
whilst ascending a 15% gradient. The frictional resistance to motion is 0.65 kN. Making use of
D’Alembert’s principle, determine:
i) the
tractive effort between the wheels and the road surface
ii) the work done in ascending the slope
iii) the average power developed by the engine

a) A vehicle of mass 700 kg accelerates uniformly from rest to a velocity of 60 kmh−1 in 10 s whilst ascending a 15% gradient. The frictional resistance to motion is 0.5 kN. Making use of D’Alembert’s principle, determine:
i) the tractive effort between the wheels and the road surface
ii) the work done in ascending the slope
iii) the average power developed by the engine.

1Kg of a fluid iss compressed reversibly according to a law pv=0.25 where p is in bar v is in m^3/Kg.The final volume is 1/4 of the initial volume.calculate the work done on the fluid and sketch the P-V diagram

5 The temperature at which the tungsten filament of a 12V and 36W lamp operates is
1730 o C 1730oC
. If the temperature coefficient of resistance of tungsten is
6×10 −3 /K 6×10−3/K
, find the resistance of the lamp at a room temperature of
20 o C 20oC



10.00Ω 10.00Ω


0.45Ω 0.45Ω


0.39Ω 0.39Ω


4.00Ω 4.00Ω

Area under a velocity time graph is distance travelled. Find, from the following formula x=t^3 + t^2 - 2t + 4
The distance travelled when an object moves through a toroidal magnet for x ms
x ms in this case = 0.4