OUR OWN HIGH SCHOOL, AL WARQA’A, DUBAI
PHYSICS SAMPLE PAPER
MECHANICAL PROPERTIES OF SOLIDS
GRADE: 11 PHYSICS (042)
SECTION A
1) Two wires A and B have the same length and area of cross-section. But Young’s modulus
of A is two times the Young’s modulus of B. Then the ratio of force constant of A to that
of B is
(a) 1 (b) 2 (c) 1/2 (d) 2
2) For a perfectly rigid body
(a) Young’s modulus is infinite and bulk modulus is zero.
(b) Young’s modulus is zero and bulk modulus is infinite.
(c) Young’s modulus is infinite and bulk modulus is also infinite.
(d) Young’s modulus is zero and bulk modulus is also zero.
3) A steel wire of length 4.5 m and cross-sectional area 3 × 10–5 m2 stretches by the same
amount as a copper wire of length 3.5 m and cross-sectional area of 4 × 10–5 m2 under a
given load. The ratio of the Young’s modulus of steel to that of copper is
(a) 1.3 (b) 1.5 (c) 1.7 (d) 1.9
Given below are two statements labelled as Assertion (A) and Reason (R). Select the most
appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
4) Assertion (A): Spring balances show incorrect readings after they had been used for a
long-time interval. Reason (R): On using for long time, spring balance loses its elastic
strength
5) Assertion (A): Strain is a unitless quantity.
Reason (R): Strain is equivalent to force.
SECTION B
6) What is a perfectly plastic body? Give an example.
7) Why does modulus of elasticity of most of the materials decrease with the increase of
temperature?
8) A wire stretches by a certain amount under a load. If the load and radius are both
increased to four times, find the stretch caused in the wire
9) No material is perfectly elastic. Why?
SECTION C
10) Define the term strain. Why it has no units and dimensions? What are different types of
strain?
11) Stress strain curve for two wires of material A and B are as shown in figure.
12) A cable is replaced by another cable of the same length and material but of half the
diameter.
(a) How does this affect its elongation under a given load?
(b) How many times will be the maximum load it can now support without exceeding the
elastic limit?
13) Define the term stress. Give its units and dimensions. Describe the different types of
stress.
(a) Which material in more ductile?
(b) Which of the two is stronger material?
(c) Which material is more brittle?
SECTION D
14) A rod of length 1.05 m having negligible mass is supported at its ends by two wires of
steel (wire A) and aluminium (wire B) of equal lengths as shown in figure. The cross-
sectional areas of wires A and B are 1.0 mm2 and 2.0 mm2 respectively. At what point
along the rod should a mass m be suspended in order to produce (a) equal stresses and
(b) equal strains in both steel and aluminium wires?
15) (a) A wire 50 cm long and 1 mm2 in cross section has the Young’s modulus, Y = 2 ×
1010 N m–2. How much work is done in stretching the wire through 1 mm? (b) What is
the length of a wire that breaks under its own weight when suspended vertically?
Breaking stress = 5 × 107 N m–2 Density of the material of the wire = 3 × 103 kg/m3
30. Two different types of rubber are found to have the stress-strain curves as shown
in figure
SECTION – E
CASE BASED MCQs
Read the passage given below and answer the following questions from 16 to 20. Stress-
Strain Curve The graph shown below shows qualitatively the relation between the stress
and the strain as the deformation gradually increases. Within Hooke’s limit for a certain
region stress and strain relation is linear. Beyond that up to a certain value of strain the
body is still elastic and if deforming forces are removed the body recovers its original
shape.
16) If deforming forces are removed up to which point the curve will be retraced?
(a) upto OA only (b) upto OB (c) upto C (d) Never retraced its path
17) In the above question, during loading and unloading the force exerted by the material are
conservative up to
(a) OA only (b) OB only (c) OC only (d) OD only
18) During unloading beyond B, say C, the length at zero stress in now equal to
(a) less than original length
(b) greater than original length
(c) original length
(d) can’t be predicted
19) The breaking stress for a wire of unit crosssection is called
(a) yield point
(b) elastic fatigue
(c) tensile strength
(d) Young’s modulus
20) Substances which can be stretched to cause large strains are called
(a) Isomers
(b) plastomers
(c) elastomers
(d) polymers
