1. To keep constant time, watches are fitted with
balance wheel made of
a) Invar
b) Stainless steel
c) Tungsten
d) Platinum
Explanation: Because dimension of invar does not varies with temperature
2. A wire is stretched by 0.01 m by a certain force F.
Another wire of same material whose diameter
and length are double to the original wire is stretched by the same force. Then its elongation
will be
a) 0.005 m
b) 0.01 m
c) 0.02 m
d) 0.002 m
Explanation:
3. The possible value of Poisson's ratio is
a) 1
b) 0.9
c) 0.8
d) 0.4
Explanation: Poisson’s ratio varies between – 1 and 0.5
4. The coefficient of linear expansion of brass and
steel are \[\alpha_{1}\] and \[\alpha_{2}\] . If we take a brass rod of
length \[l_{1}\] and steel rod of length \[l_{2}\] at 0°C, their
difference in length\[\left(l_{2}-l_{1}\right)\] will remain the same
at a temperature if
a) \[\alpha_{1}l_{2}=\alpha_{2}l_{1}\]
b) \[\alpha_{1}l_2^2=\alpha_{2}l_1^2\]
c) \[\alpha_1^2l_{1}=\alpha_2^2l_{2}\]
d) \[\alpha_{1}l_{1}=\alpha_{2}l_{2}\]
Explanation:
5. A rod is fixed between two points at 20°C. The
coefficient of linear expansion of material of rod
is \[1.1\times 10^{-5}\diagup^{\circ}C\] and Young's modulus is
\[1.2\times 10^{11}N\diagup m\] . Find the stress developed in the
rod if temperature of rod becomes 10°C
a) \[1.32\times 10^{7}N\diagup m^{2}\]
b) \[1.10\times 10^{15}N\diagup m^{2}\]
c) \[1.32\times 10^{8}N\diagup m^{2}\]
d) \[1.10\times 10^{6}N\diagup m^{2}\]
Explanation:
6. The extension of a wire by the application of load
is 3 mm. The extension in a wire of the same
material and length but half the radius by the
same load is
a) 12 mm
b) 0.75 mm
c) 15 mm
d) 6 mm
Explanation:
7. A rubber pipe of density \[1.5\times 10^{3}N\diagup m^{2}\] and
Young's modulus \[5\times 10^{6}N\diagup m^{2}\] is suspended from
the roof. The length of the pipe is 8 m. What will
be the change in length due to its own weight
a) 9.6 m
b) \[9.6 \times 10^{3}m\]
c) \[19.2 \times 10^{-2}m\]
d) \[9.6 \times 10^{-2}m\]
Explanation:
8. In which case there is maximum extension in the
wire, if same force is applied on each wire
a) L = 500 cm, d = 0.05 mm
b) L = 200 cm, d = 0.02 mm
c) L = 300 cm, d = 0.03 mm
d) L = 400 cm, d = 0.01 mm
Explanation:
9.If a spring is extended to length l, then according
to Hook's law
a) \[F=kl\]
b) \[F=\frac{k}{l}\]
c) \[F=k^{2}l\]
d) \[F=\frac{k^{2}}{l}\]
Explanation: \[F=kl\]
10. Which of the following affects the elasticity of a
substance
a) Hammering and annealing
b) Change in temperature
c) Impurity in substance
d) All of these
Explanation: All of these