LOAD AND DEPRESSION USING PIN AND MICROSCOPE AIM To verify the relation between the load and depression using non-uniform bending of a beam. APPARATUS REQUIRED A long uniform beam (usually a metre scale), two knife – edges, mass hanger, slotted masses, pin and vernier microscope. FORMULA M s = a constant where M → Load applied (mass) (kg) s → depression produced in the beam for the applied load(m) DIAGRAM Pin Beam (Metre - Scale) Slotted mass Knife edges EXPERIMENTAL SETUP OF NON - UNIFORM BENDING PIN AND MICROSCOPE Mass hanger PROCEDURE ¾ Place the two knife – edges on the table. ¾ Place the uniform beam (metre scale) on top of the knife edges.
¾ Suspend the mass hanger at the centre. A pin is attached at the centre of the scale where the hanger is hung. ¾ Place a vernier microscope in front of this arrangement ¾ Adjust the microscope to get a clear view of the pin UNIT- (XI- - ) PRACTICAL FIRST UNIT- (XI- - ) PRACTICAL FIRST - - - - Practical ¾ Make the horizontal cross-wire on the microscope to coincide with the tip of the pin. (Here mass hanger is the dead load M).
¾ Note the vertical scale reading of the vernier microscope ¾ Add the slotted masses to the mass hanger one by one in steps of . kg ( g) and corresponding readings are noted down. ¾ Repeat the experiment by removing masses one by one and note down the corresponding readings. ¾ Subtract the mean reading of each load from dead load reading.
This gives the depressions for the corresponding load M. OBSERVATIONS To find M s LOAD (kg) MICROSCOPE READINGS × − m DEPRESSION FOR M (kg) (s) M s kg m - INCREASING LOAD DECREASING LOAD MEAN MSR VSR TR MSR VSR TR M M + . M + . M + .
M + . M + . x x x x x x x − x = x − x = x − x = x − x = x − x = Mean MODEL GRAPH Load (M) vs Depression (s) A graph between M and s can be drawn by taking M along X- axis and s along Y – axis. This is a straight line.
M S x y constant Mass (kg) Depression s (m) Relation between Mass and depression UNIT- (XI- - ) PRACTICAL FIRST UNIT- (XI- - ) PRACTICAL FIRST - - - - Practical CALCULATION (i) M s = (ii) M s = (iii) M s = (iv) M s = (v) M s = RESULT ¾ The ratio between mass and depression for each load is calculated. This is found to be constant. ¾ Thus the relation between load and depression is verified by the method of non-uniform bending of a beam. UNIT- (XI- - ) PRACTICAL FIRST UNIT- (XI- - ) PRACTICAL FIRST - - - - Practical