Answer:
Free convection:
When heat transfer occurs due to density difference between fluid then this type of heat transfer is know as free convection.The velocity of fluid is zero or we can say that fluid is not moving.
Force convection:
When heat transfer occurs due to some external force then this type of heat transfer is know as force convection.The velocity of fluid is not zero or we can say that fluid is moving in force convection.
Heat transfer coefficient of force convection is high as compare to the natural convection.That is why heat force convection reach a steady-state faster than an object subjected to free-convection.
We know that convective heat transfer given as
q = h A ΔT
h=Heat transfer coefficient
A= Surface area
ΔT = Temperature difference
Answer:
1. 142.1 GPa
2. 98.52%
Explanation:
1. The modulus of elasticity of carbon-epoxy composite is calculated using the following formula:
Ec = VmEm + VfEf
where Vm: volume of Epoxy
Em: modulus of the elasticity of the epoxy
Vf: volume of carbon fiber
Ef: modulus of the elasticity of the carbon fiber
Given that :
Vm = 0.6
Em = 3.5 GPa
Vf = 0.4
Ef: 350 Gpa
Therefore Ec = (0.6 × 3.5 GPa + (0.4 × 350 GPa)
Ec = 142.1 GPa
The modulus of elasticity of carbon-epoxy composite is 142.1 GPa
2. Percentage of load carried by the carbon fibers is given by the following equation: Ff/Fc = (Ef/Ec)×Vf
where Ff is the force carried by carbon fibers, Fc is the force applied to the composite, Ec is the modulus of elasticity of the composite, Ef is the modulus of the elasticity of the carbon fiber and Vf the volume of carbon fiber.
Given that:
EF = 350 Gpa
Ec = 142.1 GPa
Vf = 0.4
Substituting the above values into the equation:
Ff/Fc = (350 GPa/142.1 GPa)×0.4 = 0.9852 = 98.52%
The percentage of load carried by the carbon fibers is there 98.52%
Answer:
b)false
Explanation:
Rolling is a process in which work piece passes through rolls to produce desired out put of the work piece.Rolling is a metal forming process.
We know that friction force is responsible for motion of work piece between rolls.If friction force is so small at the entrance side then work piece will not enter in the forming zone and forming process will not occurs.So the friction force should be high at the entrance side and low at the exit side.
So given statement is wrong.
Density = mass/volume
14 grams/42cm^3 = 1/3 or 0.333 grams/cm^3
Answer:
The correct answer is part 'c': 6.4 W/m-K
Explanation:
We know that the thermal resistance of a wall is given by
where,
L = thickness of wall
k = thermal conductivity of wall
A = Surface area of wall
Applying values we get
