CONTENTS
WEEK 1- 4 ........................................................................................................ 1
TO VERIFY THE PARALLELOGRAM LAW OF FORCES................................ 1
TO VERIFY THE TRIANGLE LAW OF FORCES ............................................... 9
TO VERIFY LAME’S THEOREM ......................................................................... 14
WEEK 5-7 ....................................................................................................... 18
DETERMINATION OF COEFFICIENT OF FRICTION...................................... 18
WEEK 8-10 ..................................................................................................... 22
DETERMINATION OF CENTER OF GRAVITY ................................................. 22
WEEK 11-12 ................................................................................................... 26
PRINCIPLE OF MOMENTS ................................................................................. 26
CONCURRENT AND NON-CONCURRENT FORCES .................................... 30
, Concept and Effect of Forces and their Movements.
WEEK 1- 4
TO VERIFY THE PARALLELOGRAM LAW OF FORCES
APPARATUS: Drawing board, two frictionless pulleys, three sets of hanger
weights, twine, geometry box, drawing pins and white paper.
THEORY
The parallelogram law of forces enables us to determine the single force
called resultant which can replace the two forces acting at a point with the
same effect as that of the two forces. This law was formulated based on
experimental results.
This law states
ates that if two forces acting simultaneously on a body at a point
are represented in magnitude and direction by the two adjacent sides of a
parallelogram, their resultant is represented in magnitude and direction by
the diagonal of the parallelogram which passes through the point of
intersection of the two sides representing the forces.
Fig. 1.1
Week 1 - 4 1
, Concept and Effect of Forces and their Movements.
Fig. 1.2
If two known forces P and Q and a third unknown force due to the weight of
the given body are made to act at a point O [Fig. 1.1]
.1] such that they are in
equilibrium, the unknown force is equal to the resultant of the two forces.
Thus, the weight of a given body can be found.
found
If the body of unknown weight R suspended from middle hanger, balances
weights. P and R suspended from. other two hangers,
The unknown weight must have a magnitude equal to the resultant of the
other two known weights.
R= + +2 cos b
Where R is the resultant force
is the angle between P and Q.
sin Ɵ
tan =
+ cos Ɵ
Where α is the angle between P and R.
Here P and Q are two weight hangers attached by a thread and passed
over the pulleys. The third weight hanger R is attached at the midpoint (O)
of the thread.
Week 1 - 4 2
, Concept and Effect of Forces and their Movements.
PROCEDURE
1. Set a flexible cord to the arrangement of pulleys as shown in Fig. 1.2.
2. Weigh the three weight boxes accurately and attach two of them to
theends of the cord.
3. Put enough weights on the weight boxes (F1 and F2) so that the sag of
the cord becomesnegligible.
4. Attach a third weight box within the pulley and put loads on it.
5. After a pre-assigned total load W (not exceeding the sum of the two end
loads), allow thesystem to come into equilibrium (to rest).
6. Now fix a white paper on the drawing board with the help of drawing pins
7. Trace carefully the direction of force P, Q, R with the help of pencil
without parallax error.
8. Remove the paper from the board.
9. Draw the lines to meet at the points (O)
10. The forces P,Q,R are represented by the line OA, OB and OD as shown
in fig. 1.3 below.
11. Construct the parallelogram with the help of scale.
12. Take a unit on scale with compass and draw an arc on P and Q. From
this point draw another arc intersecting.
13. Now join these arcs from P and Q and draw OC line like in fig. 1.4
14. Draw diagonal OC to the parallelogram and take a unit on the scale
with the compass and draw arc on D as shown in fig. 1.5
Week 1 - 4 3
WEEK 1- 4 ........................................................................................................ 1
TO VERIFY THE PARALLELOGRAM LAW OF FORCES................................ 1
TO VERIFY THE TRIANGLE LAW OF FORCES ............................................... 9
TO VERIFY LAME’S THEOREM ......................................................................... 14
WEEK 5-7 ....................................................................................................... 18
DETERMINATION OF COEFFICIENT OF FRICTION...................................... 18
WEEK 8-10 ..................................................................................................... 22
DETERMINATION OF CENTER OF GRAVITY ................................................. 22
WEEK 11-12 ................................................................................................... 26
PRINCIPLE OF MOMENTS ................................................................................. 26
CONCURRENT AND NON-CONCURRENT FORCES .................................... 30
, Concept and Effect of Forces and their Movements.
WEEK 1- 4
TO VERIFY THE PARALLELOGRAM LAW OF FORCES
APPARATUS: Drawing board, two frictionless pulleys, three sets of hanger
weights, twine, geometry box, drawing pins and white paper.
THEORY
The parallelogram law of forces enables us to determine the single force
called resultant which can replace the two forces acting at a point with the
same effect as that of the two forces. This law was formulated based on
experimental results.
This law states
ates that if two forces acting simultaneously on a body at a point
are represented in magnitude and direction by the two adjacent sides of a
parallelogram, their resultant is represented in magnitude and direction by
the diagonal of the parallelogram which passes through the point of
intersection of the two sides representing the forces.
Fig. 1.1
Week 1 - 4 1
, Concept and Effect of Forces and their Movements.
Fig. 1.2
If two known forces P and Q and a third unknown force due to the weight of
the given body are made to act at a point O [Fig. 1.1]
.1] such that they are in
equilibrium, the unknown force is equal to the resultant of the two forces.
Thus, the weight of a given body can be found.
found
If the body of unknown weight R suspended from middle hanger, balances
weights. P and R suspended from. other two hangers,
The unknown weight must have a magnitude equal to the resultant of the
other two known weights.
R= + +2 cos b
Where R is the resultant force
is the angle between P and Q.
sin Ɵ
tan =
+ cos Ɵ
Where α is the angle between P and R.
Here P and Q are two weight hangers attached by a thread and passed
over the pulleys. The third weight hanger R is attached at the midpoint (O)
of the thread.
Week 1 - 4 2
, Concept and Effect of Forces and their Movements.
PROCEDURE
1. Set a flexible cord to the arrangement of pulleys as shown in Fig. 1.2.
2. Weigh the three weight boxes accurately and attach two of them to
theends of the cord.
3. Put enough weights on the weight boxes (F1 and F2) so that the sag of
the cord becomesnegligible.
4. Attach a third weight box within the pulley and put loads on it.
5. After a pre-assigned total load W (not exceeding the sum of the two end
loads), allow thesystem to come into equilibrium (to rest).
6. Now fix a white paper on the drawing board with the help of drawing pins
7. Trace carefully the direction of force P, Q, R with the help of pencil
without parallax error.
8. Remove the paper from the board.
9. Draw the lines to meet at the points (O)
10. The forces P,Q,R are represented by the line OA, OB and OD as shown
in fig. 1.3 below.
11. Construct the parallelogram with the help of scale.
12. Take a unit on scale with compass and draw an arc on P and Q. From
this point draw another arc intersecting.
13. Now join these arcs from P and Q and draw OC line like in fig. 1.4
14. Draw diagonal OC to the parallelogram and take a unit on the scale
with the compass and draw arc on D as shown in fig. 1.5
Week 1 - 4 3
