A steel rod of length L and diameter D, fixed at both ends, is uniformly heated to a temperature rise of ΔT. The Young's modulus is E and the coefficient of linear expansion is a. The thermal stress in the rod is(Mechnical Engg.)
Zero
αΔT
EαΔT
EαΔTL
Answer: Option D
Due to Af rise in temperature of steel rod of length L, increase in length
ΔL = α × L × Δt
Since, both ends are fixed, thermal stress will be produced in the steel rod.
∴ Thermal stress σ = E × ε = E × α × Δt
In terms of Poisson's ratio (v), the ratio of Young's modulus (E) to shear modulus (G) of elastic materials is(Mechnical Engg.)
2(1+v)
2(1-v)
1/2 (1+v)
1/2 (1-v)
Answer: Option A
We know that Young's modulus (E) is connected to shear modulus (G) as
E = 2G (1 + v)
where v = Poisson's ratio.
∴ Rigid ratio E/G = 2(1+v)
The total area under the stress-strain curve of a mild steel specimen tested upto failure under tension is a measure of (Mechnical Engg.)
Ductility
Ultimate strength
Stiffness
Toughness
Answer: Option D
The total area under tensile stress-strain curve of a specimen upto failure is a measure of toughness of the material.
The depth of flow in an alluvial channel is 1.5 m. If critical velocity ratio is 1.1 and Manning's n is 0.018,the critical velocity of the channel as per Kennedy's method is (Civil Engg.)
0.713m/s
0.784 m/s
0.879 m/s
1.108m/s
Answer: Option B
y = 1.5m,n=0.018
Critical velocity as per Kennedy's equation
v = 0.55 m/s064
= 6.55×1.1×(1.5)064
= 0.784 m/s
A sprinkler irrigation system is suitable when
the land gradient is steep and the soil is easily erodible
the soil is having low permeability
the water table is low
the crops to be grown have deep roots
Answer: Option A
Sprinkler irrigation has the highest efficient method of irrigation for the land having high gradient and soil is likely to be eroded due to flow of water but not suitable at high wind speed.
While applying the rational formula for computing the design discharge, the rainfall duration is stipulated as the time of concentration because
this leads to the largest possible rainfall intensity
this leads to the smallest possible rainfall intensity
the time of concentration is the smallest rainfall duration for which the rational formula is applicable
the time of concentration is the largest rainfall duration for which the rational formula is applicable.
Answer: Option A
Time of concentration (tc) is the time when entire catchment starts contributing to surface run-off at channel and this is the minimum time required. So, smallest rainfall duration for which the rational formula is applicable.
