Question

In: Other

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.

Expert Solution

For this we will first assume that only the cylindrical portion of the cup is transferring heat and the bottom circle which will be resting on the ground won't contribute to heat transfer

Thermal conductivity of styrofoam cup, K =0.033 w/mk

Now

Rate of heat transferred by styrofoam cup = Heat absorbed by the surrounding

Hstyrofoam_cup =H_surrounding

Now Tin = 70 ^oC, Tsurr =20 ^oC, H = 8 w/m^2oC, D = 5 cm

Ri = 2.5 cm

Ro =Ri + thickness = 2.5 + 0.3 = 2.8 cm, L = 7 cm = 0.07 m,

substituting all the known data in above heat transfer equation to obtain the value of T_out

Do = Di +2*thickness = 5 cm + 2(0.3) = 5.6 cm = 0.056 m

Tout = 48.26 oC

Hence outer surface of the cup is 48.26 ^oC

Rate of heat transfer

= 2.784 Watts

Amanda K answered 2 years ago

The inner and outer surface temperatures of a glass window 5 mm thick are 15 and...

The inner and outer surface temperatures of a glass window 5 mm thick are 15 and 5°C. The thermal resist- ance of the glass window due to conduction is Rt,cond = 1.19 × 10−3 K/W. What is the rate of heat loss through a 1 m × 3 m window? What is the thermal conductivity of the glass?

A toroid with inner diameter of 3 cm, outer diameter of 5 cm, and height of...

A toroid with inner diameter of 3 cm, outer diameter of 5 cm, and height of 0.1 cm is made of a body-centered-cubic (bcc) paramagnetic material with lattice parameter equal to 0.5 nm. The toroid is wrapped by a copper wire in 20 turns. If each atom of the magnetic material has a magnetic moment of 1.5µB (Bohr Magneton), (a) (1.5 pt) What is the saturation magnetization (in A/m) of the material? (b) (1.5 pt) If a current of 2...

The inner and outer diameter of a single core cable are 3 cm and 8.5 cm...

The inner and outer diameter of a single core cable are 3 cm and 8.5 cm The insulated with two materials having relative permittivity of 5 and 3.5 respectively with corresponding maximum electric stresses of 35 kV/cm and 25 kV/cm. Draw the configuration and calculate: a) the radial thickness of each insulating layer. b) the safe working voltage of the cable. c) draw the voltage and electric stress as a function of radial distance from center to metal sheath.

A hypodermic needle is 4.0 cm long and has an inner diameter of 0.25 mm. Assume...

A hypodermic needle is 4.0 cm long and has an inner diameter of 0.25 mm. Assume the syringe contents have the same properties as water and is at 20 C. a. What pressure is needed to deliver a steady flow of 0.1 cm3 per second? b. If the inner diameter of the needle were increased by 20%, what pressure would be needed to deliver the same flow?

A 5.0 mL syringe has an inner diameter of 5.5 mm , a needle inner diameter...

A 5.0 mL syringe has an inner diameter of 5.5 mm , a needle inner diameter of 0.22 mm , and a plunger pad diameter (where you place your finger) of 1.2 cm. A nurse uses the syringe to inject medicine into a patient whose blood pressure is 140/100. Assume the liquid is an ideal fluid. Part A What is the minimum force the nurse needs to apply to the syringe? Part B The nurse empties the syringe in 4.9...

A 4.5 mL syringe has an inner diameter of 6.0 mm , a needle inner diameter...

A 4.5 mL syringe has an inner diameter of 6.0 mm , a needle inner diameter of 0.29 mm , and a plunger pad diameter (where you place your finger) of 1.2 cm. A nurse uses the syringe to inject medicine into a patient whose blood pressure is 140/100. Assume the liquid is an ideal fluid. A. What is the minimum force the nurse needs to apply to the syringe? B. The nurse empties the syringe in 5.0 s ....

A freezer planned to be insulated with 10 cm thick Styrofoam. At what rate the compressor...

A freezer planned to be insulated with 10 cm thick Styrofoam. At what rate the compressor must remove heat from the freezer to keep the inside temperature at -18 degrees C in a place where the air temperature is 22 degree. The freezer dimensions are 2m tall,1m wide, and 1m deep.

A brass ring with inner diameter 2.00 cm and outer diameter 3.00 cm needs to fit...

A brass ring with inner diameter 2.00 cm and outer diameter 3.00 cm needs to fit over a 2.00 cm-diameter steel rod, but at 20∘C the hole through the brass ring is 48 μmtoo small in diameter. To what temperature, in ∘C, must the rod and ring be heated so that the ring just barely slips over the rod?

Two 15-cm-diameter metal disks separated by a 0.69-mm-thick piece of Pyrex glass are charged to a...

Two 15-cm-diameter metal disks separated by a 0.69-mm-thick piece of Pyrex glass are charged to a potential difference of 1100 V . What is the surface charge density on the disks? What is the surface charge density on the glass?

‏1. The impeller in a centrifugal pump has inner diameter as 125 mm and outer diameter...

‏1. The impeller in a centrifugal pump has inner diameter as 125 mm and outer diameter as 270 mm. The pump runs at 1400 rpm. The vane angles of impeller at inlet and outlet are 17° and 30° respectively. The water enters the impeller radially and velocity of flow is constant. Determine the work done by impeller per unit weight of water.