Question 1 :
A toy car travels in a horizontal circle of radius 2a, kept on the track by a radial elastic string of unstretched length a. The period of rotation is T. Now the car is speeded up until it is moving in a circle of radius 3a. Assuming that the string obeys Hooke's law then the new period will be

Question 2 :
Assertion: The stress-strain behaviour varies from material to material. Reason: A rubber can be pulled to several times its original length and still returns to its original shape.

Question 3 :
Assertion (A): Steel is more elastic than rubber.<br/>Reason (R) : Under a given deforming force, steel is deformed less than rubber.<div><br/>A) Both Assertion and Reason are true and the reason is correct explanation of the assertion<br/>B)Both Assertion and Reason are true, but reason is not correct explanation of the assertion<br/>C) Assertion is true, but the reason is false<br/>D) Assertion is false, but the reason is true</div>

Question 4 :
Assertion: Stress is the internal force per unit area of a body. Reason: Rubber is more elastic than steel.

Question 5 :
A steel cable with a radius $2cm$ supports a chairlift at a ski area. If the maximum stress is not to exceed ${ 10 }^{ 8 }N\quad { m }^{ -2 }$, the maximum load the cable can support is

Question 6 :
Change in shape of a body caused by the application of stress is called:<br>

Question 10 :
A spring is made of steel and not of copper because

Question 11 :
<span>The property of a material due to which shape is changed permanently is known as:</span><br/>

Question 13 :
Fill in the blank.<br/>In a technical sense a substance with a ________ elasticity is one that requires a ______ force to produce a distortion-for example, a steel sphere. <br/><br/>

Question 15 :
A wire is stretched to double its length. The strain is :

Question 16 :
Assertion: For small deformations, the stress and strain are proportional to each other. Reason: A class of solids called elastomers does not obey Hooke's law.

Question 17 :
<span>Change in the shape of a body caused by the application of a force (stress) is called as :</span><br/>

Question 19 :
Assertion: If we apply force to a lump of putty or mud, they have no gross tendency to regain their previous shape. Reason: This type of substances are called plastic substances.

Question 20 :
A spring with force content $k$ is initially stretched by ${ x }_{ 1 }.$ If it is further stretched by ${ x }_{ 2 },$ then the increase in its potential energy is.

Question 21 :
Which property of an object cannot be changed by applying forces?

Question 23 :
According to Hooke's law of elasticity, if stress is increased, then the ratio of stress to strain :

Question 24 :
The property to restore the natural shape or to oppose the deformation is called :

Question 27 :
Assertion: Strain is a unitless quantity. Reason: Strain is equivalent to force

Question 29 :
A wire of length 1 m fixed at one end has a sphere attached to it at the other end. The sphere is projected horizontally with a velocity of $\sqrt{9g}$. When it describes a vertical circle, the ratio of elongations of the wire when the sphere is at the top and bottom of the circle is :

Question 31 :
Assertion: Identical springs of steel and copper are equally stretched. More work will be done on the steel spring Reason: Steel is more elastic than copper.

Question 32 :
Length of a wire is increased by 1 mm on the application of a given load. If same load is applied to another wire of same material but of length and radius twice that of the first then increase in its length will be

Question 33 :
The SI unit of stress is same as the SI unit of

Question 34 :
Breaking stress of a material is $2 \times 10 ^ { 8 } N / m ^ { 2 }$. What maximum length of the wire of this material can be so that the wire does not break my own weight? [Density of material $= 5 \times10 ^ { 3 } k g / m ^ { 3 } $]<br>

Question 35 :
<p><span>A steel rope has length $L$, area of cross-section $A$, Young's modulus $Y$ and density as $ d$. </span>It is pulled on a horizontal frictionless floor with a constant horizontal force $F=\dfrac{dALg}{2}$ applied at one end. Find the strain at the midpoint.</p>