MCQOPTIONS
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MCQOPTIONS
This section includes 5 Mcqs, each offering curated multiple-choice questions to sharpen your Heat Transfer knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A centrifugal pump which circulates a hot liquid metal at 500 degree Celsius is driven by a 3600 rpm electric motor. The motor is coupled to the pump impeller by a horizontal steel shaft of dia 25 mm. Let us assume the motor temperature as 60 degree Celsius with the ambient air at 25 degree Celsius, what length of shaft should be specified between the motor and the pump? It may be presumed that the thermal conductivity of the shaft material is 35W/m K and that the convective film coefficient between the steel shaft and the ambient air is 15.7W/square m K |
| A. | 38.96 cm |
| B. | 54.76 cm |
| C. | 23.76 cm |
| D. | 87.43 cm |
| Answer» B. 54.76 cm | |
| 2. |
Two rods A and B of the same length and diameter protrude from a surface at 120 degree Celsius and are exposed at air at 25 degree Celsius. The temperatures measured at the end of the rods are 50 degree Celsius and 75 degree Celsius. If thermal conductivity of material A is 20W/ m K, calculate it for B |
| A. | 31.13W/m K |
| B. | 41.13W/m K |
| C. | 51.13W/m K |
| D. | 61.13W/m K |
| Answer» D. 61.13W/m K | |
| 3. |
A rod of 10 mm diameter and 80 mm length with thermal conductivity 16W/ m K protrudes from a surface at 160 degree Celsius. The rod is exposed to air at 30 degree Celsius with a convective coefficient of 25W/square m K. How does the heat flow from this rod get affected if the same material volume is used for two fins of the same length? Assume short fin with insulated end |
| A. | 12.25 % |
| B. | 25.6 % |
| C. | 23.4 % |
| D. | 21.2 % |
| Answer» E. | |
| 4. |
Fin is insulated at the tip . What does that mean? |
| A. | Less heat is transferred from the tip |
| B. | Heat will transferred from tip only |
| C. | More heat is transferred from the tip |
| D. | No heat is transferred from the tip |
| Answer» E. | |
| 5. |
The relevant boundary conditions in case of heat dissipation from a fin insulated at the tip are |
| A. | t = t <sub>0</sub> at x = 0 and d t/d x = 0 at x = 0 |
| B. | t = t <sub>0</sub> at x = 0 and d t/d x = 0 at x = 1 |
| C. | t = t <sub>0</sub> at x = 1 and d t/d x = 0 at x = 1 |
| D. | t = t <sub>0</sub> at x = infinity and d t/d x = 0 at x = infinity |
| Answer» C. t = t <sub>0</sub> at x = 1 and d t/d x = 0 at x = 1 | |