Answer:
The question doesn't make sense
Explanation:
If you want to ask something please do make it understandable.
Answer:
2000-7000 * 6% = - 0,000126
Answer:
time required for cooling process = 0.233 hours
Explanation:
In Transient heat conduction of a Sphere, the formula for Biot number is;
Bi = hL_c/k
Where L_c = radius/3
We are given;
Diameter = 12mm = 0.012m
Radius = 0.006m
h = 20 W/m²
k = 40 W/m·K
So L_c = 0.006m/3 = 0.002m
So,Bi = 20 x 0.002/40
Bi = 0.001
The formula for time required is given as;
t = (ρVc/hA)•In[(T_i - T_(∞))/(T - T_(∞))]
Where;
A is Area = πD²
V is volume = πD³/6
So,
t = (ρ(πD³/6)c/h(πD²))•In[(T_i - T_(∞))/(T - T_(∞))]
t = (ρDc/6h)•In[(T_i - T_(∞))/(T - T_(∞))]
We are given;
T_i = 1200K
T_(∞) = 300K
T = 450K
ρ = 7800 kg/m³
c = 600 J/kg·K
Thus, plugging in relevant values;
t = (7800 x 0.012 x 600/(6 x20) )•In[(1200 - 300)/(450 - 300)]
t = 468•In6
t = 838.54 seconds
Converting to hours,
t = 838.54/3600
t = 0.233 hours
Answer:
The torque on the section is 563.373 Nm
Explanation:
The torque in the section can be calculated through torsion formula. The torsion formula is given as follows:
Torque = T = τJ/ r
where,
r = maximum radius = 5.5 cm/2 = 2.75 cm = 2.75 x 10^-2 m
τ = maximum shear stress = 22 MPa = 22 x 10^6 Pa
J = Polar moment of inertial = π/2 (ro^4 - ri^4)
J = π/2 (0.0275^4 - 0.01875^4) m^4 = 7.042 x 10^-7 m^4
Therefore:
T = (7.042 x 10^-7 m^4)(22 x 10^6 Pa)/(2.75 x 10^-2 m)
<u>T = 563.373 Nm</u>