MCQ
3841. The materials having same elastic properties in all directions are called- [PPA-19]
ব্যাখ্যা: Isotropic material means a material which have same or identical properties in all direction. Such as metal and glass.
ideal materials
isotropic materials
elastic materials
uniform materials
3842. If a material expands freely due to heating it will develop- [PPA-19]
ব্যাখ্যা it, it will expand. Since it is unconstrained it expands freely and no stresses occur. That is the thermal strain is equal to the total strain. Thus, the mechanical strain is zero and thus the "thermal stress" is zero.
thermal stresses
no stresses
tensile stress
bending
3843. The unit of moment of inertia of an area is-[ IMES-18]
ব্যাখ্যা: Moment of intertia,
Ad^2= (mxm)x m^2= m^4
kg.m²
kg/m²
kg.m² s
m^4
3844. If two forces of 3kg and 4kg act at right angles to each other, their resultant force will be- [MOCA-19]
ব্যাখ্যাঃ
R=√P^2+Q^2+2PQCOSO
=√9+16+2x3 x4 x cox 90°
= √2
= 5kg
7kg
14kg
5kg
7kg
3845. If the resultant of two equal force has the same magnitude as either of the force, then the angle between the two forces is- [BADC-18]
ব্যাখ্যা: Let the two forces be found F₂ at an angle x where
IF₁I =I F₂I = IRI
We know,
Resultant force,
R^2 = P² + Q^2+2PQcos0
F₁ ^2= F₁ ^2 + F₁ ^2+2 F₁ ^2cos0
F₁ ^2=2 F₁ ^2(1+cos0)
Cancelling F₁ ^2 on both sides
1=2(1+cos0)
Cos0 = 1/2
0=120°
30°
120°
60°
90°
3846. A material capable of absorbing large amount of energy before fracture is known as- উত্তর (PPA-19)
ব্যাখ্যা: The ability of a metal to deform plastically and to absorb energy in the process before fracture is termed toughness.
ductility
shock proof
toughness
resilience
3847. The highest value of specific heat is found in- [PPA-19]
ব্যাখ্যা: Among all the four given liquids that is kerosene, methane, alcohol and water only water has the highest specific heat. The value of specific heat of water is 4.18 Joules per gram.
Alcohol
Kerosene
Methane
Water
3848. The ultimate tensile stress for mild steel is - the ultimate compressive stress. [MES-18]
ব্যাখ্যা: The ultimate tensile stress of mild steel is more than the ultimate compressive stress. Young modulus of a wire will be equal to stress for unit strain.
equal to
more than
less than
none of these
3849. Young's modulus is the property of- [PPA-19]
ব্যাখ্যা: Young's modulus is a mechanical property that measures the stiffness of a solid material.
Gas only
Solid only
Liquid and solid
Liquid only
3850. Which of the following materials is most elastic? [PPA-19]
ব্যাখ্যা: Both rubber and steel have elastic properties but steel is more elastie than rubber because steel comes back to its original shape faster than rubber when the deforming forces are removed. Steel has a higher elastic modulus (Young's modulus) than rubber.
rubber
steel
plastic
brass
3851. The resultant of two forces P & Q (Such that P > Q) acting along the same straight line but in opposite direction is given by- [MOD-20]
ব্যাখ্যা: When a system of force is acting on an object, the difference between the forces is called the Resultant force. Example-A 3N force to the left and 10N force the right given a resultant force of 7N of the right.
P+Q
P-Q
P/Q
Q/P
3852. Deformation per unit length in the direction of force is known as- [PPA-19]
ব্যাখ্যা: Linear strain of a deformed body is defined as the ratio of the change in length of the body due to the deformation to its original length in the direction of the force.
Strain
Lateral strain
Linear strain
Stress
3853. The poisson's ratio for steel varies from- [BREB-17; MES-18]
ব্যাখ্যা: Poisson's ratio values for different materiais.
Material Possion's ratio
Clay 0.30-0.45
Stainless steel 0.30-0.31
Steel (MS) 0.27-0.30
Castiron 0.21-0.26
0.22 to 0.27
0.32 to 0.42
0.25 to 0.33
0.31 to 0.34
3854. The unit of force in S.I. system of units is- [BB-20, BADC-18, MOD-20]
ব্যাখ্যা: Sl unit of force: Newton
SI-based unit of force: kg-m/sec^2
Dyne
Watt
Newton
Kilogram
3855. Two forces of 6 and 8kg act at right angles to each other, the resultant force will be- [PPA-19]
ব্যাখ্যা: Given, F₁ =6kg. F₂=,8 kg. 0=90°
Resultant force,
R = √F₁^2+,F₂^2 + 2F₁F₂ cos0
√6^2+8^2+2x6x8 xcos90° = 10 kg.
10
14
41
28
3856. The polar moment of inertia of a solid circular shaft of diameter (D) is- [MOD-20]
πd³/16
πd³ /32
πd4/64
πd4/32
3857. The hottest planet is- [BB-20]
ব্যাখ্যা: Venus is the hottest planet in the solar system. Mercury-800°F (430°C) during the day, 290°F (-180°C) at (471°C), Saturn-minus 218"F (-138°C). night, Jupiter-minus 162°F (-108°C), Venus-880°F
Mercury
Saturn
Jupiter
Venus
3858. 1 meter = ft ? [MOD-20]
3.2808
3.3505
3.3802
3.500
3859. 1MPa (Mega Pascal) = ?[BREB-20]
ব্যাখ্যা:। MPa
=1x10^6 Pa
10^6 N/m²
=10^6 kg/ 9.81 m
10 ×2.20 lb/ 9.81 x(39.37)^2 inch^2
=144.68 =145 ps
[1 MPa = 100^6 Pa)
[1 Pa = 1 N/m²]
[1 kg = 9.81N]
(1 kg = 2.20 lb)
[1m=39.37 inch]
145 psi
131 psi
401 psi
100 psi
3860. The unit of force in SI system is- [BB-20]
ব্যাখ্যা: As per the second law of motion proposed by Newton, force is defined as the product of mass and acceleration. In both the Sl system and in MKS system, the unit of mass is kilogram and the unit of acceleration is m/s. Therefore, the unit of force is kg m/s, which is what we refer to as Newton or N.
Newton
Kilogram
Dyne
Watt