Chandan Ms Lab Assignment

8/14/2019 Chandan Ms Lab Assignment

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CHANDAN KUMAR INDIVISUAL ASSIGNMENT Page 1

APIIT SD INDIA LEVEL 0

Contents

EXPERIMENT NO. 1.......................................................................................................................... 2

CENTRE OF GRAVITY............................................................................................................ 2

Conclusion:................................................................................................................................. 3

EXPERIMENT NO. 2..................................................................................................................... 4

COEFFICIENT OF STATIC FRICTION................................................................................... 4

Result:-........................................................................................................................................ 6

EXPERIMENT NO. 3..................................................................................................................... 7

TRIANGLE OF FORCE EXPERIMENT.................................................................................. 7

Result:......................................................................................................................................... 9

EXPERIMENT NO. 4................................................................................................................... 10

BELL CRANK LEVER EXPERIMENT.................................................................................. 10

Result:....................................................................................................................................... 12


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EXPERIMENT NO. 1

CENTRE OF GRAVITY

AIM: To locate the center of gravity for given objects, having uniform distribution of

mass.

Apparatus required:

Centre of gravity apparatus. Different types of uniform shapes.

Figure of centre of gravity apparatus

Theory:Centre of gravity of a body can be defined as the point through which resultants

of the gravitational force acting on the body acts or is concentrated for any orientation of

the body.


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Procedure:

Hang the object from any point and drop a weighted string from the samepoint.

Draw a line on the object along the string. Repeat the procedure for different points on the object. Now you have the lines drawn on the object which intersect at a particular point.

The centre of gravity is the point where the lines intersect. Repeat the steps 2 to 6 for given different objects having different shapes. Tabulate the results in a table.

Observation:

Shape Name Distance x, from geometric Centre Distance y, from geometric

Centre

Trapezoid 10 8.5

Circle 0 0Semi-circle 11 5.5

Triangle 8 6

Precaution:

Make sure that the strings of the apparatus are free from tension and are freelyhanged.

The weight or pointer hanged on to the string should be free from any tension

Make sure that the shapes are also hung freely and the string is properly fallingupon them.

`

Conclusion: Since from the above experiment we come to know about the most

significant property of the centre of gravity, and conclude that the total mass of the body

is concentrated on it.


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EXPERIMENT NO. 2

COEFFICIENT OF STATIC FRICTION

AIM:To determine the coefficient of friction under sliding condition between polished

glass surface and wooden block.

Apparatus Required:

Inclined plane apparatus. Different weight blocks Lubricating oil.

Figure of Inclined plane apparatus

Labelling:

Inclined track Load Hanger Inclined angle indicator Set of Carrier Set of weights


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Theory: Friction is defined as the imaginary force which opposes the cause of motion

that is it opposes the motion of a body when it moves or tends to move due to the action

of an external force on the body. While kinetic friction can be defined as the frictional

force that develops between mating surfaces when subjected to external force but there isno relative motion between them.

Procedure:

Level the inclined plane set in a horizontal position. Next, choose specimen and record its weight R. Then place the specimen onto the horizontal plane, in the mid span. Connect a cord to the specimen hook as provided. Run the cord over the pulley and place a hanger (0.1N) on to the other end of the

cord.

Put sufficient weights on to the hanger till it balances the specimen weightwithout sliding down the plane.

Repeat step 2 until step 6 for different specimens. Take note of the weight + hanger.

Observation:

Serial number F (gm) R (gm) 1 40 171.5 0.233

2 35 141.5 0.247

3 35 131.5 0.266

Formula used for calculating the static coefficient of friction is:

= f / RN

Calculation:

Average -:

(0.233+0.247+0.266)/3 = 0.746/3 = 0.248

Precaution:

The string or thread of the apparatus should be free from any tension.


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The pulley should be well lubricated. The weights should be added step by step and it should be ensured that the block

should not slide and the readings should be taken just before it slides.

Result:-Hence from the above experiment we can determine the coefficient of static

friction between two surfaces ( i.e between a polished glass surface and wooden block).


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EXPERIMENT NO. 3

TRIANGLE OF FORCE EXPERIMENT

AIM: To determine the experimental resolution of three static coplanar forces. To

show that if the forces are in equilibrium the triangle is closed and to show that if two

forces are known in magnitude and direction, the third must be the resultant of the

triangle of forces.

Apparatus Required:

Triangle of force apparatus. Different weight blocks.

Figure of Triangle of force apparatus-


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Theory: For equilibrium in a triangular force, the system will be at equilibrium only

when if the sum of forces acting at an equilibrium, then the algebraic sum of their

resolved part in any two perpendicular direction s are separated zero.

If three-force body is subjected to only three forces. For the equilibrium, the actingforces must be concurrent and must from a closed triangle.

F1

Law of sines can then be used to solution of force

SinA/A=sinB/B=sinC/C F2

Where in=sinB=sinC=angle between 2 forces F3

Procedure:

Place the apparatus on a level table. Sketch the desirable free body diagram. Loosen the turning knob of the pulley bracket (E). Mount the three pulley bracket

on the protractor plate.

Set the pulley bracket to desirable angle. Tighten the turning knob.

Adjust both of the screws at the side of the bracket. Do not over tighten norloosen the screws. Make sure the pulley can turn smoothly.

Place the ring (A) to the centre of the protractor. Place the three cords to the three pulleys. Place a weight hanger (B) to each of the cord. Place the desirable weights to each of the hanger and observe the movement of

the ring.

If the ring touches the centre rod, this implies that the system is not inequilibrium position.

Repeat the experiment with different angles and different weights applied.


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Observation:

1 2 3

F1 1() F2 2() F3 3()

Case 1 0.45 0 0.5 122 0.45 257

Case 2 0.45 0 0.4 97 0.55 224

Case 3 0.45 0 0.45 105 0.55 240

Calculations

fx = 4410* sin0+3920*sin230+3920*sin110

= 4410*1+3920*sin230+3920*sin110

= 4410+3920*(-0.76) +3920(0.93)

= 5076.4

fy =4410*cos0+3920*cos230+ 3920*cos110

= 4410*1+3920*sin230+3920*(-0.34)

=4410+3920*(-0.64)+3920*(-0.34)

= 568.4

Precaution:

The string or thread of the apparatus should be free from any tension. The pulley should be well lubricate The weights should be added step by step. Resolution of force is to be maintained.

Result:The resolution of three static coplanar forces is determined and the forces are in

equilibrium in the triangle is proved.


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EXPERIMENT NO. 4

BELL CRANK LEVER EXPERIMENT

Aim:To verify the principle of moment using Bell Crank Lever.

Apparatus Required:

Bell Crank Lever apparatus. Different weight blocks Hanger

Figure of Bell Crank Lever apparatus -

Theory:Moment of force about a point is defined as the turning tendency of a force

about that point. It is measured by the product of force and the perpendicular distance of

line of action of force from that point.

Mathematically M= FxL


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Where F= force acting on the body

L= perpendicular distance between the referenced point and the line of action of

force.

Procedure:

Make the longer arm of the lever horizontal by adjusting with wing nut providedat the end of spring balance longer screw, by using a level when there is no load

on longer arm.

Note the initial spring balance reading. Place the stirrup on any one groove of the arm and hang a small weight (W) on

the hook. This will make the longer arm move down ward and the spring balance

will show some reading on balance.

Note the final spring balance reading. Change the position of load and repeat the steps 3 to 4 for different loads and

calculate the moments.

Tabulate the results in a table.

Sr. No. Load(F)Final Spring

reading(W)

Distance ofload from

hinge point(x)

y

1 100+73.5 10013 22.55

2 100+73.5 20023 22.55

3 100+73.5 30033 22.55

4 100+73.5 400

43 22.55

Formula

Use the formulae below to calculate the moments on bell crank lever:

M1= Spring Force (F)x

M2= Weight (W)y

M1 M2

2255.5 2255.5

3990.5 3990.5


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5725.5 5725.5

7460.5 7460.5

For example:

Calculations:

Here, M1= F*x;

M2 = W*y;

M1= 173.5*13=2255.5

M2 = 100*22.55=2255.5

M1=M2

(Hence proved)

Precaution

Check for zero error. Add the weight gradually There should be minimal disturbance as long as the pointer is concerned Only one person must take all the readings, because eye judgement will vary from

individual to individual

Weight should not touch the table The pointer should exactly coincide with the mark on the bell crank lever. The optimum starching of spring should be kept in mind The apparatus should be kept on smooth and level surface. Proper lubrication of the joints of two arms of the lever so as to reduce frictional

force.

Result:

From the value obtained above, its clear that the observed and calculated values

obtained for the value of spring forces are nearly equal and within the permissible

experimental error limit.

Hence, the law of moment stating that the moment of a force about an axis is

equal to the sum of moment of its components about the same axis has been verified.

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