Mechanical Engineering Answers

G(s)= s+2/ s2 −s−1

a) Draw the block diagram of the system. Make sure you show the reference input 𝑅(𝑠), the output

𝐶(𝑠) and the unity feedback.

 A flat belt, 8 mm thick and 100 mm wide transmits power between two pulleys, running at 1600 m/min. The mass of the belt is 0.9 kg/m length. The angle of lap in the smaller pulley is 165° and the coefficient of friction between the belt and pulley is 0.3. If the maximum permissible stress in the belt is 2 MN/m2, find : 1. maximum power transmitted ; and 2. initial tension in the belt

The power transmitted between two shafts 3.5 metres apart by a cross belt drive round the two pulleys 600 mm and 300 mm in diameters, is 6 kW. The speed of the larger pulley (driver) is 220 r.p.m. The permissible load on the belt is 25 N/mm width of the belt which is 5 mm thick. The coefficient of friction between the smaller pulley surface and the belt is 0.35. Determine : 1. necessary length of the belt ; 2. width of the belt, and 3. necessary initial tension in the belt.

 An open belt 100 mm wide connects two pulleys mounted on parallel shafts with their centers 2.4 m apart. The diameter of the larger pulley is 450 mm and that of the smaller pulley 300 mm. The coefficient of friction between the belt and the pulley is 0.3 and the maximum stress in the belt is limited to 14 N/mm width. If the larger pulley rotates at 120 r.p.m., find the maximum power that can be transmitted.

1.How will you apply a chemical that needs to be ingested by immobile insects?

A. Spray the chemical below the canopy

B.Apply the chemical so that it completely covers the plant

C. Apply the chemical on same parts of the plant

D. Apply the chemical on the stem of the plant

E.Spray the chemical in the air

2. One of the following is not true of internal combustion engine.

A.More mechanical simplicity and lower weight / power ratio

B. it could be started and stopped in a a short time

C. Its thermal efficiency is higher than other heat engines

D.Its initial cost is high

E. It does not need auxiliary equipment, such as boiler and condenser

The brakes on the tractor apart from being basically a safety feature, are also used for:

a.Turning the vehicle

b. Reversing the vehicle

c. Speeding up the vehicle

d. Reducing the power of the vehicle

e. Disconnecting the power from the engine

In a jib crane, the jib and tie rod are 6 m and 5 m long respectively. The height of the crane post is 3 m. When a weight (W) 317 N is suspended from the crane and the tie rod remains horizontal.

Determine the tension in Tie rod (only magnitude, in N)?

 a jib crane, the jib and tie rod are 6 m and 5 m long respectively. The height of the crane post is 3 m. When a weight (W) 317 N is suspended from the crane and the tie rod remains horizontal.

Determine the angle θ (unit in degrees)?

Design a typical cotter joint to transmit a load of 50 kN in tension or

compression. Consider that the rod, socket and cotter are all made of a

material with the following allowable stresses:

Allowable tensile stress sy = 150 MPa

Allowable crushing stress sc = 110 MPa

Allowable shear stress ty = 110 MPa.

The velocity profile of a fluid over a plate is parabolic with its vertex 200 mm from the plate, where the velocity is 1.2 m/s.Calculate the velocity gradients and shear stresses at 50 mim and 200 mm from the plate, if the viscosity of the fluid is 0,8 N. s/m.