CBSE
Multiple Choice QuestionsAssertion: Stress is the internal force per unit area of a body.
Result: Rubber is more elastic than steel.
If both the assertion and reason are true and reason is a correct explanation of the assertion.
If both assertion and reason are true but assertion is not a correct explanation of the assertion.
If the assertion is true but the reason is false.
If both assertion and reason are false.
The breaking strength of a rod of diameter 2 cm is 2x 105 N. Then that for rod of same material but diameter 4 cm will be
2 × 105 N
1 × 105 N
8 × 105 N
0.5 × 105 N
A body weighs 200 N at the surface of earth. If it be placed in an artificial satellite revolving at height where acceleration due to gravity is half of that at earth's surface. It will weigh
2109 N/m2
2 108 N/m2
2106 N/m2
2 104 N/m2
A bob of mass 10 kg is attached to wire 0.3 m long. Its breaking stress is 4.8 x107 N/m2. The area of cross-section of the wire is 10-6 m2. The maximum angular velocity with which it can be rotated in a horizontal circle is
8 rad/s
4 rad/s
2 rad/s
1 rad/s
A rubber cord 10 m long is suspended vertically. How much does it stretch under its own weight? (Density of rubber is 1500 kg/m3, Y = 5 × 108 N/m2, g = 10 m/s2)
15 × 10-4 m
7.5 × 10-4 m
12 × 10-4 m
25 × 10-4 m
A metallic rod of Young's modulus 2x1011 N/m2 undergoes a strain of 0.5%. Then the energy stored per unit volume in the rod will be
2.5 × 106 J/m3
5 × 108 J/m3
2.5 × 108 J/m3
0.5 × 1011 J/m3
A brass rod of cross-sectional area 1 cm2 and length 0.2 m is compressed lengthwise by a weight of 5 kg of Young's modulus of elasticity of brass is 1 x 1011 N/m2 and g = 10 m/s2, then increase in the energy of the rod will be
10-5 J
2.5 × 10-5 J
5 × 10-5 J
2.5 × 10-4 J
A metal wire of length l, area of cross-section A and Young's modulus Y behaves as a spring of spring constant k given by
A wire fixed at the upper end stretches by length by applying a force F. The work done in stretching is
FΔl
2 FΔl
The breaking stress of a wire depends upon
length of the wire
material of the wire
radius of the wire
shape of the cross-section
