1. The stress represented by sin (t) + 4 belongs to which category?
a) Alternating Stresses
b) None of the mentioned
c) Repeated Stresses
d) Reversed Stresses
Explanation: The mean as well as the amplitude value is non zero hence it belongs to Alternation Stresses category which is the other name of Fluctuation Stresses.
2. The stress represented by cos (t) belongs to which category?
a) Fluctuating Stresses
b) Alternating Stresses
c) Repeated Stresses
d) Reversed Stresses
Explanation: Half cycle is in tensile stress and other half in compressive stress, hence it belongs to Reversed Stresses Category.
3. If the mean stress value for a sinusoidal stress function is zero, then this type of stress falls in which category?
a) Fluctuating Stresses
b) Alternating Stresses
c) Repeated Stresses
d) Reversed Stresses
Explanation: If mean is to be zero, then there must be compressive as well as tensile stresses and hence belongs to reversed stresses category.
4. The phenomenon of decreased resistance of the materials to fluctuating stresses is the main characteristic of _____ failure.
a) Fracture
b) Fatigue
c) Yielding
d) None of the mentioned
Explanation: Fatigue failure of the material is the failure at low stress levels under fluctuating syresses.
5. Fatigue failure is time dependent failure.
a) True
b) False
Explanation: Fatigue failure is defined as time delayed fracture under cyclic loading.
6. There is sufficient plastic deformation prior to fatigue failure, which gives a warning well in advance.
a) True
b) False
Explanation: Fatigue cracks are not visible until they reach the surface and by that time the failure has already taken place. Material nevers enters in the plastic range.
7. A power screw is only used to convert rotary motion into linear motion and not for transmitting power.
a) True
b) False
Explanation: Power screw converts the motion from rotary to linear and is used for power transmission.
8. Depending upon the holding arrangement, power screws operate in how many different arrangements.
a) 2
b) 3
c) 4
d) 5
Explanation: There are two types of arrangements. In one screw rotates while nut remains stationary and vice versa.
9. A power screw has no problem of wear as there is very less amount of friction associated.
a) True
b) False
Explanation: Wear is a serious problem in power screws as there is high friction in threads.
10. V threads are highly recommended for fastening as well as power transmission purpose.
a) Yes
b) Never
c) In some cases
d) Can’t be stated
Explanation: In fastening, high frictional force is required and hence V threads are used whereas in power transmission, reduction in frictional forces is required.