Strength of Materials - GATE practice papers - Mechanical

1)   Calculate the normal stress acting on the plane of maximum shear stress, considering the following state of stress shown in the figure. (Marks: 02)

State of Stress

- Published on 19 Oct 15

a. 30 MPa compression
b. 30 MPa tension
c. 15 MPa compression
d. 15 MPa tension
Answer  Explanation 

ANSWER: 15 MPa compression

Explanation:
Normal stress acting on the plane of maximum shear stress will be, (Taking compression as positive)

σn = (σx± σy) / 2 =(50 – 20) / 2 = +15

that is 15 MPa compression.


2)   A spring of radius 1 cm obeys Hooke's law. A mass of 2 kg is attached to the spring. Calculate the extension of the spring. The spring constant k is 110 N/m
- Published on 19 Oct 15

a. 17.81 m
b. 0.1781 cm
c. 0.1781 m
d. 0.1781 mm
Answer  Explanation 

ANSWER: 0.1781 m

Explanation:
According to the Hooke's law force applied to extend or compress a spring is directly proportional to change in length of the spring. Therefore F = – kX where k is spring constant. By using this formula and taking force applied F = mg = 2 × 9.8 =19.6 N and k = 110 N/m we can fine X.


3)   Poisson's ratio is the ratio of ______(Marks: 01)
- Published on 19 Oct 15

a. longitudinal strain to lateral strain
b. lateral strain to longitudinal strain
c. longitudinal stress to lateral strain
d. lateral stress to longitudinal strain
Answer  Explanation 

ANSWER: lateral strain to longitudinal strain

Explanation:
The ratio of lateral strain to longitudinal strain has a constant value and it is called as Poisson's ratio. Poisson's ratio is denoted by v


4)   What is stress? (Marks: 01)
- Published on 19 Oct 15

a. internal resistance offered by a body against deformation
b. external resistance offered by a body against deformation
c. internal force offered by a body against deformation
d. external force offered by a body against deformation
Answer  Explanation 

ANSWER: internal resistance offered by a body against deformation

Explanation:
Stress is an internal resistance offered by a body or a material against deformation. It is a resisting force per unit area.


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