Determine the frictional resistance, Mechanical Engineering

Determine the frictional resistance:

 (i) A train having weight 400 kN is running up an inclined path of 1 in 100 at a steady speed of 54 km/hour. If the frictional resistance is 0.5% of its weight, Find out the H. P. (output) of its engine.

 (ii) If the steam is cut off whereas the train is ascending this gradient, how far it shall go up the plane before coming to rest. Determine the frictional resistance to remain constant during its travel.

Solution

Figure illustrated the idealized body of train on the gradient (∠ α) moving up the plane under the driving force P.

Frictional force F is, thus, down the plane.

F = (0.5/100) × 400 = 2 kN.

Component of weight W along with the plane is W sin α ≈ 400 ×(1/100)=4KN

Gradient or slope = tan α =1/100 , α being very small and sin α ≈ tam α.

 Therefore the driving force P = F + W sin α = 6 kN.

Velocity of train = 54 km/hr

V = 54 × 1000/3600

 = 15 m / sec.

 (i)        ∴ H. P. exerted = P × V/746     = (6000 × 15)/ 746  =120.64

 (ii)       While the steam is cut off, P = 0

Retarding force = F + W sin α

                          = 6 kN.

Retardation = a

          W = 400 kN

∴ W a /g= 6

or Retardation = 6 × 9.8/400  = 0.147 m / sec2 .

When the train comes to rest, V2 = 0

(V 2)2 = (V 1)2  - 2 a s

0 = 152 - 2 × 0.147 s

∴ Distance (s) travelled up the gradient = 765 metres.

N. B.    Part (ii) of the example may also be solved by using energy principle as follows :

W. D. against resistance = KE available with the train

∴ P × s = W V2 /2 g

∴ 6 s = 400 × 152 /2 × 9.8

or,

s = 765 metres

Posted Date: 1/29/2013 7:08:51 AM | Location : United States







Related Discussions:- Determine the frictional resistance, Assignment Help, Ask Question on Determine the frictional resistance, Get Answer, Expert's Help, Determine the frictional resistance Discussions

Write discussion on Determine the frictional resistance
Your posts are moderated
Related Questions
Nitrides, Silicides and Sulfides Nitrides contain very high melting point but initiate to oxidize at low temperature. They have poor resistance also to chemicals. Boron nitrid

State Hook's law: Sol.: It states that when material is loaded within the elastic limit, the stress is proportional to strain produced by the stress. This means that the rat

Determine the moment of resistance of the flitched beam: A flitched beam consists of a wooden beam of width 120 mm & depth 250 mm & mild steel plates of thickness 10 mm & widt

EQUIPMENT FOR RESISTANCE WELDING-Single phase vs three phase The resistance welding machines can be connected either across 440 V mains (across two lines) or three phase mains.

During the test run of prototype machine we found out a few issue occurred due to blasting room design problem. The blasting room design is too quartet, this design had cause the b

#question.what are process of annealing? .

Throttle Valve: The throttle valves control the quantity of mixture supplied to the cylinder. This is controlled by throttle grip with the help of a cable. When we open throttle

Q. Show Bolt Material? Bolt material must be selected with adequate yield strength at the operating temperature to provide the required strength to properly seat the gasket. It

Calculate the support reactions of beam: Q: Bending moment diagram (BMD) of the simple supported beam can be given as shown in figure given below. Calculate the support reac

what is tooling economics, machine economics and optimization