Engineering Answers

How many sheets of a dielectric are necessary to make a condenser having a capacity of 5.5nF when the sheets are 15cm x 30cm in area and 0.29cm thick? Use k = 8

To a closed system 150 kJ of work is supplied. If the initial volume is 0.6 m3 and pressure of the system changes as p = 8 – 4V, where p is in bar and V is in m3, determine the final volume and pressure of the system.

An element in biaxial stress is subjected to stresses σx = −16 MPa and σy =42 MPa, as shown in the figure. Using Mohr's circle, determine:

(a) the stresses acting on an element oriented at a slope of 1 on 2.5 (see Fig Q1)

(b) the maximum shear stresses and associated normal stresses. Show all results on sketches of properly oriented elements.

It is required to lift a load of 1.2 tons through a height of 320

mm by using a screw jack under the following condition:

• The available material of the screw is plain carbon steel

which has elastic strength in tension and compression of

200 MPa and in shear 120 MPa respectively.

• The available material of the nut is phosphor-bronze for

which the elastic limit may be taken as 100 MPa in

tension, 90 MPa in compression and 80 MPa in shear.

• The bearing pressure between the nut and the screw is

not to exceed 20 N/mm?.

Design and draw the screw jack. The design should include

the design of:

1) The screw,

2) Nut,

3) Handle and Cup, and

4) Body.

Draw to full scale an isometric and multi-views for the screw

jack.

The design report should include the following:

• Calculation sheet.

• Detail drawing (soft).

• References including material data sheets and used

curves and tables.

• Assume any missing data.

15. The tooth thickness of a gear is 0.5 in. and its circular pitch 1.0 in. Calculate the dedendum of the gear. (SHOW ANSWER AND SOLUTION)

8. Find the standard distance between sprocket having 4 in and 16 in diameters. (SHOW ANSWER AND SOLUTION)

8. Find the standard distance between sprocket having 4 in and 16 in diameters.

7. A chain with speed 800 fpm has driving sprocket turns at 900 rpm. If the pitch of chain is ¾ in, find the number of teeth of driving sprocket. (SHOW ANSWER AND SOLUTION)

13. A pump that operates a head of 30 m is used to deliver 80 liters per second of water at an efficiency of 85%. The pump is driven by a diesel engine by means of chain and sprocket with a service factor of 1.3. If horsepower per strand is 25, find the approximate number of strands needed. (SHOW ANSWER AND SOLUTION)

In an ideal constant volume cycle, the pressure and temperature at the beginning of Compressions are 97 kN/m2 and 40°C, respectively. The compression ratio is 7: 1. The heat supplied during the cycle is 1200 kJ/kg of working fluid. Determine (a) the maximum temperature attained in the cycle, (b) the thermal efficiency of the cycle, and (c) the work done during the cycle/kg of working fluid. Assume ɤ = 1.4 and Cv, = 0.718 kJ/kg K