Page 68 - Physics - XI

7. Slowly add weights in the pan and gently tap near the roller till you fi nd that the roller just begins to
move downwards along the inclined plane. Note the total weights placed (p ) in the pan.
1
8. Further increase the weights placed in the pan till the roller just begins to move upwards on gently
tapping the plane. Note the total weights placed (p ) in the pan in this case also.
2
9. Now, increase the angle of inclination in steps of 5° each, making it 35°, 40°, 45°, 55°, and 60° and
repeat steps 7 to 9.

10. Note all the observations in the observation table.

Observations
Least count of spring balance = _____ g wt

Zero error of spring balance = (e) = _____ g wt
Zero correction of spring balance = (–e) = _____ g wt

Observed weight of the roller = w =_____ g wt
0
Corrected weight of the roller = w = w + (–e) = _____ g wt
0
Observed weight of the pan = p = _____ g wt
0
Corrected weight of the pan = p = p + (–e) = _____ g wt
0
Table for calculation of Force W and Angle of Inclination θ
S. Angle of sin θθ w sin θθ Weight placed in the W = p + p W = p + p 2 Force acting Error
1
2
1
No. inclination = mg sin θθ pan when roller moves (g wt) (g wt) on roller (W – mg
'θθ' (g wt) downwards upwards W W W 2 sin θ)θ)
1
p p 2 (g wt)
1 2
(degree) (g wt) (g wt) (g wt)
1.
2.
3.
4.
5.
6.
7.

Y

Graph

Plot a graph between sin θ and W, taking sin θ along X-axis and W
along Y-axis. The graph between sin θ and W comes to be a straight
line. It verifi es that Scale used on:

W ∝ sin θ W (g. wt) X-axis 1 cm = ...
Y-axis 1 cm = ... g wt
X
0.5 sin θ
Fig. 10.3: Graph between W and sin θ

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