Mechanical Engineering Answers

1. A diesel engine has a compression ratio of 18 and cut- off takes place at 5% the stroke . calculate the air standard efficiency. Y=1.4

Two 5m x 5m thin-walled parallel plates are separated by a distance of 1 mm. Air (properties shown below at the external fluid) flows over the TOP AND BOTTOM of the parallel plate stack. You may assume fully developed hydrodynamic and thermal boundary layers between the parallel plates. Using the drawing and information below, what is the outlet mean temperature of the internal fluid?

In a crank and slotted lever mechanism, the driving crank is 35 mm long, and the time ratio of cutting stroke to return stroke is 1.6. If the length of working stroke of the ram is 110 mm, find the distance between the fixed centers, and the slotted lever length.

It is important that the karts can brake effectively. They use drum brakes where a solid circular drum of mass 4.0 kg and radius 0.15 m is rotating at an angular speed of 22 rad s−1 about an axis when a ‘braking’ torque is applied to it which brings it to rest in 5.8 s.

Calculate

i) its angular deceleration when the braking torque is applied.

ii) the moment of inertia of the drum about the axis shown

𝐼 = 1 𝑚𝑟2 2

iii) the resultant torque that causes it to decelerate.

Your go karts have a mass of 450kg and travel around a circular curve on a flat, horizontal track at a radius of 42 m.

a) Draw a diagram to show the go kart on the track and add an arrow to show the direction of the frictional force needed for the car to travel around the curve at a radius of 42 m.

b) The maximum frictional force between the tyres and the road is equal to 20% of the weight of the car and driver. Calculate the coefficient of friction when an adult of mass 70kg is driving the kart.

c) Calculate maximum angular velocity at which the car can travel round the curve at a constant radius of 42 m.

d) Calculate the maximum linear velocity.

e) You decide that this is not nearly fast enough and decide to create a banked track of 12O, what is the maximum linear velocity now?

f) Describe qualitatively how this could change if a child were driving the kart.

Determine (input the letter only) what functions does the following expression belong.

The questions items has the format of f(x), f(m, n).

A: one to one, not onto B: onto, not one to one

C: one to one, onto D: Neither one to one nor onto

E: Not a function

Given for solving the f(S): f(x) = x^2/3 

The questions items has the format of S={1,2,3}.

Format of answer: f(S) = {1, 2, 3} 

1. f(x) = x + 2, Z → Z.
2. f(x) = 4x+5, R → R.
3. For the given sequence, provide a simple formula or rule that generates the terms of the sequence: 2, 3, 7, 25, 121, 721, 5041, 40321,..
4. f(x) = 2x + 1, R→ R.
5. f(x) = x^3 , R → R.
6. f(x)= x + 2 / x^3 + 8, Z → Z,
7. S = {1, 5, 7, 11}
8. S = {2, 6, 10, 14}.

determine the heat evolution inside a horizontal tube heated at the bottom at a temperature of 40 degree celsius, diameter of the tube is negligible and tube length is 1m, v =1cm/sec

In a slider crank mechanism, the length of crank OB and connecting rod AB are 125 mm and 500 mm respectively. The centre of gravity G of the connecting rod is 275 mm from the slider A. The crank speed is 600 r.p.m. clockwise. When the crank has turned 45° from the inner dead centre position, determine:

1. velocity of the slider A,

2. velocity of the point G, and

3. angular velocity of the connecting rod AB. Use relative velocity method.

[Ans. 6.45 m/s ; 6.75 m/s ; 10.8 rad/s]

The crank and connecting rod of a reciprocating engine are 200 mm and 700 mm respectively. The crank is rotating in clockwise direction at 120 rad/s. Find with the help of Klein’s construction: 1. Velocity and acceleration of the piston, 2. Velocity and acceleration of the midpoint of the connecting rod, and 3. Angular velocity and angular acceleration of the connecting rod, at the instant when the crank is at 30° to I.D.C. (inner dead center). [Ans. 15.24 m/s, 2880 m/s2 ; 16.8 m/s, 2779.2 m/s2 ; 29.66 rad/s, 1913.14 rad/s2]

In a slider crank mechanism having a stroke length of 30 cm and an obliquity ratio of 4, the crank is rotating uniformly in anti-clockwise direction. The angular velocity of crank is 52 rad/sec. The crank has turned through angle of 48.45 degree from IDC position. Determine using Klein’s construction:

a)   Acceleration of slider    [259.584 m/s2]

b)   Angular velocity and angular acceleration of connecting rod   [8.75rad/s, 500rad/s2]

c)    Velocity of slider    [6.812m/s]