Question

In: Mechanical Engineering

A 50 cm *50 cm copper slab 6.25 mm thick has uniform temperature of 300°C. Its...

A 50 cm *50 cm copper slab 6.25 mm thick has uniform temperature of 300°C. Its temperature is suddenly lowered to 36°C. (quenched in water) Take The conductivity k-370 W/mK, the density rho-9100 kg/m³, the specific heat c-0.38 K/kg°C, the convection coefficient h=90 W/m2C.

1- Calculate the surface area, As

a - 0.125 m2
b- 0.5125 m2
c- 0.25 m2
d- 0.5 m2

2. Calculate the volume,

a- 0.0015625 m3
b- 0.003205 m3
c- 0.00078125 m3
d- 0.03587 m3

3. Calculate the characteristic length, Lc

a- 0.0625 m
b- 0.3125 mm
c- 0.00625 m
d- 0.003125 m

4. Calculate the Biot number, Bi

a- 0.00125
b- 0.00074
c- 0.00152
d- 0.000760

5. Calculate the thermal diffusivity, a (alpha)

a- 0.000107 m2/s
b- 0.0000107 m2/s
c- 0.0107 m2/s
d- 0.00107 m2/s

6. Calculate the constant of time, t (tau)

a- 1200.7 s
b- 0.125 s
c- 240.14 s
d- 120.07 s

7. Calculate the time required for the plate to reach the temperature of t1

a- 1560s
b- 312 s
c- 156 s
d- 0.156s

8. Calculate the time required for the plate to reach the temperature of t2

a- 586.275 s
b- 5862.75 s
c- 1172.55 s
d- 0.586 s

9. Calculate the temperature at the surface at time 100s , Ts 2

a- 279 ْ C
b- 210 ْ C
c- 36 ْ C
d- 150.8 ْ C

10. Calculate the total energy transferred from this plate during the first 100s , Q

a- 806.204 kJ
b- 485.841 kJ
c- 1139.874 kJ
d- 1.426 kJ

Expert Solution

samet mamat answered 2 months ago

A copper ball of temperature 100 °C is immersed to a water bath of 50 °C....

A copper ball of temperature 100 °C is immersed to a water bath of 50 °C. After 10 minutes the temperature of the ball is 80 °C and the temperature of the water is 60 °C. You may assume that Newton’s Law of Cooling is obeyed and all the heat lost by the ball is absorbed by the water. Find the equilibrium temperature of the ball as a function of time.

A Copper plate that is 588mm wide and 48 mm thick is to be reduced in...

A Copper plate that is 588mm wide and 48 mm thick is to be reduced in a single pass in a two high rolling mill by using a 321mm diameter roll. The coefficient of friction at roll workpiece interface is 0.14 and the roll rotates at 107rpm. The rolling process is performed above the recrystallization temperature of the material and the width of the plate does not change during this operation. What is the minimum final thickness (mm) possible

A 2.0 mm -diameter, 50 cm -long copper wire carries a 4.5 A current. What is...

A 2.0 mm -diameter, 50 cm -long copper wire carries a 4.5 A current. What is the potential difference between the ends of the wire?

prestressed road bridge of span 16.74 m consists of a concrete slab of 420 mm thick...

prestressed road bridge of span 16.74 m consists of a concrete slab of 420 mm thick with parallel post-tensioned cables, in each of which the force at transfer is 440 kN. If the bridge is required to support a uniformly distributed applied load of 43.37kN/m2 , with tensile stress in the concrete not exceeding 0.85 N/mm2 at any time. Calculate the maximum horizontal spacing of the cables, their distance from the soffit of the slab at mid-span and their lowest...

A planar slab of thickness of 5.00 cm has a uniform volume charge density of 7.20×10-2...

A planar slab of thickness of 5.00 cm has a uniform volume charge density of 7.20×10-2 C/ m3. Find the magnitude of the electric field at all points in space both inside and outside the slab, in terms of x, the distance measured from the central plane of the slab. What is the field for x = 1.25 cm? What is the field for x = 10.00 cm?

A thick steel slab (ρ= 7800 kg/m3, c= 480 J/kg·K, k= 50 W/m·K) is initially at...

A thick steel slab (ρ= 7800 kg/m3, c= 480 J/kg·K, k= 50 W/m·K) is initially at 300°C and is cooled by water jets impinging on one of its surfaces. The temperature of the water is 25°C, and the jets maintain an extremely large, approximately uniform convection coefficient at the surface. Assuming that the surface is maintained at the temperature of the water throughout the cooling, how long will it take for the temperature to reach 50°C at a distance of...

The inner surface of a 5 cm diameter, 3 mm thick, and 7 cm high styrofoam...

The inner surface of a 5 cm diameter, 3 mm thick, and 7 cm high styrofoam cup is at 70 °C. the outer surface is exposed to air at 20 °C. the surface heat transfer coefficient associated with the outer surface is 8 w/m2 °C. Determine The heat transfer rate through the cylindrical surface of the cup. The outer surface temperature of the cup.

A 2.8 mm -diameter copper wire carries a 31 Acurrent (uniform across its cross section). A)...

A 2.8 mm -diameter copper wire carries a 31 Acurrent (uniform across its cross section). A) Determine the magnetic field at the surface of the wire. B) Determine the magnetic field inside the wire, 0.50 mm below the surface. C) Determine the magnetic field outside the wire 2.5 mm from the surface.

copper fin 1.0 mm thick is placed on a circular tube. The out side daiameter of...

copper fin 1.0 mm thick is placed on a circular tube. The out side daiameter of the tube is 2.5 cm. The fin long is 8 mm and the thermal conductivity is 379 W/m °C. The tube wall is maintained at 473K. The fin is exposed to an environment with h = 30 W/m "C and T∞= 288K. %3D Calculate the heat lost by the fin.

At a certain temperature T1, a (1.8922x10^2) mm rod of a copper-nickel alloy has a resistivity...

At a certain temperature T1, a (1.8922x10^2) mm rod of a copper-nickel alloy has a resistivity of (2.770x10^1) x 10-8 Ω-m. For pure copper, the resistivity at 0°C is 1.58 x 10-8 Ω-m and the change in resistivity per degree increase in temperature is 6.50 x 10-11 (Ω-m)/°C. The value of A for nickel in copper is 1.18 x 10-6 Ω-m and the coefficient of thermal expansion of this alloy is (1.543x10^1) x 10-6(°C)-1. If the resistivity of this alloy...