Elasticity

Q.

Give two examples of the turning effect of force.

Q. A wire suspended vertically from one of its ends is stretched by attaching a weight of $200\text{N}$ to its lower end. If the weight stretches the wire by $1\text{mm}$, then elastic energy stored in the wire is

1. $0.2\text{J}$
2. $10\text{J}$
3. $0.1\text{J}$
4. $20\text{J}$

Q.

Which of the following is an amorphous solid?

1. Graphite

2. Quartz glass

3. Chrome alum

4. Silicon carbide

Q. A wire can sustain a weight of $20\text{kg}$ before breaking. If the wire is cut into two equal parts, each part can sustain a weight of

1. $10\text{kg}$
2. $20\text{kg}$
3. $05\text{kg}$
4. $25\text{kg}$
   

Q. For the given figure, if the dimensions of the two wires are same, but materials are different, then Young's modulus is

1. more for $A$ than $B$
2. more for $B$ than $A$
3. equal for $A$ and $B$
4. None of these

Q. A stone of mass $20\text{g}$ is projected from a rubber catapult of length $0.1\text{m}$ and area of cross section ${10}^{–6}{\text{m}}^2$ stretched by an amount $0.04\text{m}$. The velocity of the projected stone is ____ $\text{m/s}$.
(Young's modulus of rubber $=0.5\times {10}^9\text{N}/{\text{m}}^2$)

Q. When a uniform metallic wire is stretched the lateral strain produced in it is $\beta$. If $\nu$ and $Y$ are the Poisson's ratio and Young's modulus for the wire, then elastic potential energy density of wire is

1. $\frac{Y{\beta }^2}{2}$
2. $\frac{Y\nu {\beta }^2}{2}$
3. $\frac{Y{\nu }^2}{2\beta }$
4. $\frac{Y{\beta }^2}{2{\nu }^2}$

Q.

When is a body said to be perfectly elastic?

Q. $I-V$ characteristic of a copper wire of length $L$ and area of cross-section $A$ is shown in the figure. The slope of the curve becomes

1. more if a wire of steel of the same dimension is used
2. more if the length of the wire is increased
3. less if the length of the wire is increased
4. more if the experiment is performed at higher temperature

Q. Which is more elastic-rubber or steel?

Q. The property of a material to restore its natural shape or to oppose deformation is called

1. Rigidity
2. Elasticity
3. Plasticity
4. Deformability

Q.

If the Youngs modulus of the material is 3 times its modulus of rigidity, then its volume elasticity will be

1. Zero

2. Infinity

3. 

4. 

Q.

Which of the following factors can bring about a change in the elastic properties of a material?

1. Hammering and annealing

2. Change in temperature

3. Impurity in substance

4. All of the above

Q. A block of mass $m$ is suspended by different springs of force constant shown in figure.
Let time period of oscillation in these four position be $T_1,T_2,T_{3}and{T}_4$. Then,
(Consider springs to be massless.)

1. $T_1=T_2=T_4$
2. $T_1=T_2\text{and}{T}_3=T_4$
3. $T_1=T_2=T_3$
4. $T_1=T_3\text{and}{T}_2=T_4$

Q. How can centre of mass of a body be outside.?

Q. A pan with set of weights is attached with a light spring. When disturbed, the mass-spring system oscillates with a time period of 0.6s. When some additional weights are added then time period is 0.7s. The extension caused by the additional weights is approximately

1. 2.45 cm
2. 1.38 cm
3. 3.5 cm
4. 1.75 cm

Q. If stretching force F1 is applied on a vertical metal wire then its length is L1 and if force F2 is applied on it then its length becomes L2 . The real length of wire is

Q. A rubber cord has a cross-sectional area $1{\text{mm}}^2$ and total unstretched length $10.0\text{cm}$. It is stretched to $12.0\text{cm}$ and then released to project a missile of mass $5.0\text{g}$. Taking Young's modulus $Y$ for rubber as $5.0\times {10}^8{\text{N/m}}^2$. The velocity of projection is _______${\text{ms}}^{-1}$.

Q.

What name is given to the solid having a regular, repeating molecular pattern?

Q. A neutron with an energy of $4.6\text{MeV}$ collides with protons and is retarded. Assuming that upon each collision the neutron is deflected by ${45}^{\circ }$ The number of collisions which will reduce its energy to $0.23\text{eV}.$ nearly is (integer only.)

Q. An elastic string has a mass $M$ suspended at its lower end, the upper being fixed to a support. When the mass is pulled down over a short distance and let go, then it executes SHM with Time period given by $T=2\pi \sqrt{\frac{l_1}{g}}$ Where $l_1$ is the elongation of the string. Now the mass $m$ is added to the mass $M$, then it is found that time period of oscillation $T_2,$ such that $\frac{T_1}{T_2}=\frac{5}{4}$. Then the ratio $16m:M$ is
Given $Y$ is the Young modulus of elasticity, $L$ be the original length of string.

Q.

Substances whose atoms or molecules are arranged in a definite pattern are known as -----------------

Q. A steel wire of length $5\text{m}$ is suspended vertically, stretches by $20\text{mm}$ when mass of $60\text{kg}$ is attached to the lower end. Find the elastic potential energy gained by the wire. (take $g=10{\text{m/s}}^2$)

1. $0.6\text{J}$
2. $6\text{J}$
3. $60\text{J}$
4. $600\text{J}$

Q.

The elastic limit point on the stress-strain curve appears?

Q. Why is steel is more elastic than rubber?

Q. Materials which do not have a certain organized arrangement of atoms and molecules are also known as

1. Crystalline solids
2. Amorphous solids
3. Ionic solids
4. Metallic solids

Q. The figure shows the stress-strain plot for an aluminium wire, which is stretched by a machine pulling in opposite directions at the ends of the wire. The wire has an initial length of $0.8\text{m}$ and initial cross-sectional area of $2.0\times {10}^{-6}{\text{m}}^2$. How much work is done by the machine on the wire to produce a strain of $1.0\times {10}^{-3}$ $?$

1. $54.4\text{mJ}$
2. $56\text{mJ}$
3. $108.8\text{mJ}$
4. $128\text{mJ}$

Q. In an elastic solid, the work done by an external force to produce strain is $800\text{J}$. If the external force is removed, then the elastic potential energy of the solid will be -

1. $800\text{J}$
2. $200\text{J}$
3. $400\text{J}$
4. $0\text{J}$

Q. Select the correct statement(s) :-

1. Crystalline solids melt at fixed temperature.
2. Particles in amorphous solids are arranged in irregular pattern.
3. Crystalline solids have regular and definite shape.
4. None of these.

Q.

A tie bar $50\text{mm}\times 8\text{mm}$ is to carry a load of 80 kN. A specimen of the same quality steel of cross -sectional area $250m{m}^2$ was tested in the laboratory. The maximum load carried by the specimen was 125 kN. The factor of safety in the design is.

1. 2.5