Physics Practicals - For Class IX and X (Science Group) - PRACTICAL 02: Determine the Resultant of two vectors by (Gravesend's apparatus).

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PRACTICAL 02:

• Determine the Resultant of two vectors by (Gravesend's apparatus).

APPARATUS:

• Gravesend's Apparatus i.e:
  i) Vertical drawing board
  ii) Two fixed pulleys (clamped to the top)
• Three sets of 20 gm slotted weights with hanger
• Plane mirror strip
• Drawing paper
• Thumb pin
• Light string about 1 meter long
• Meter Scale
• Geometry box

THEORY:
Those physical quantities, which are completely, specified only when direction is also mentioned along with magnitude and units are known as vector.

RESULTANT VECTOR:
Vectors, which gives combined effect of two or more vectors, called resultant vectors.

TRIANGULAR LAW OF VECTOR ADDITION:
If two vectors represent two sides of the triangle, then third side of triangle in reverse order will be the resultant of the two sides.

PARALLELOGRAM LAW OF VICTOR ADDITIONS:
According to this law the diagonal of parallelogram represents the resultant of two adjacent of the parallelogram.

METHOD: (1 + 1 MARKS)

• Fix drawing paper in the middle of the vector board and place it vertically.
• Adjust the thread, carrying a set of weights at each end, over two pulleys.
• The small thread carrying third set of weights at the center of the first two thread.
• Place plane mirror under one of the thread keeping one eye close and mark two points 'A' and 'B', such that the two points and the image of thread lie exactly under the thread.
• Similarly mark C, D and E, F under other two thread.
• Join A and B, C and D. and E and F and extend them to meet at point O.
• Select suitable scale (10 gm-wt = 1 cm) and draw arcs OP and OQ corresponding to their weights.
• Draw PX and QX parallel to OP and OQ.
• Join P and X and 0 and X.
• OX is the resultant of OP and PX.
• Find magnitude of OX by multiplying its length with the scale.
• Repeat above procedure by using unequal weights and find their resultant.

OBSERVATIONS: (1 + 1 MARKS)

OBS	WEIGHT OF RIGHT HAND SIDE (OP) gm-wt	WEIGHT OF LEFT HAND SIDE (OQ) gm-wt	RESULTANT WEIGHT (OX) gm-wt
1.
2.

FIGURE:

RESULT:
1. The magnitude of the resultant of two equal vectors each of ______ is _______ gm-wt.
2. The magnitude of two unequal vectors of _______ gm-wt and _______ is ______ gm-wt.

PRECAUTIONS:

• Board must be exactly vertical.
• Standard weights must be used.
• Pulleys must be friction less.

Special Thanks to Sir Sajjad Akber Chandio