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P. 139
Mechanical properties of matter
ICT corner
Visit https://phet.colorado.edu and select the simulation titled Density
and Buoyancy to help students visualise and demonstrate the concept
of density of a substance.
.Chapter summary
1. Elasticity is the ability of a deformed material to regain its original size and shape
after the deforming force is removed.
2. Hooke’s law states that ‘provided that the elastic limit is not exceeded, the extension
of elastic material is directly proportional to the force applied’.
3. Surface tension is the ability of the surface of a liquid to behave like a fully
stretched elastic skin. This elastic nature of the surface of a liquid is caused by
the attraction of the liquid molecules at the surface.
4. Capillarity is the tendency of a liquid to rise and fall in narrow tubes or to be drawn
into small openings. It occurs when the adhesive forces between the liquid and the
walls of the tube are larger than the cohesive forces between the liquid molecules.
Revision exercise 6 (a) between O and P (b) at P
Section A (c) between P and Q (d) at Q
1. Answer all questions by writing the (ii) When a force is applied to a given
letter of the most correct answer material, the material returns to its
(i) Where on the graph is the limit of original shape after the force is
proportionality for an elastic solid? removed. This behaviour is termed as:
(a) Plastic deformation
(b) Elastic deformation
Q
(c) Irreversible deformation
(d) Viscous deformation
Extension (m) a beaker of water. The water level
(iii) A glass capillary tube is placed in
inside the tube is higher than the
P
water level outside due to:
(a) Cohesion (c) Surface tension
(b) Adhesion (d) Elasticity
(iv) A weight of 2.0 N is hung from a
spring. The extension produced is
6.0 cm. The 2.0 N weight is removed
O
Load (N)
and an 8.0 N weight is hung from the
Figure 6.17 spring. The spring does not pass its
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