A spherical interplanetary probe, with a diameter of 2 m, is sent out into the solar system. The probe surface is made of material having an emissivity of 0.9 and an absorptivity of 0.1. Signals from the sensors monitoring the probe surface temperatures are indicating an average value of $−40^\circ C$ for a space temperature of 0 K. If the electronics inside the probe is generating heat at a rate of $100 W/m^3,$ determine the incident radiation rate on the probe surface.

An electric current of 5 A passing through a resistor has a measured voltage of 6 V across the resistor. The resistor is cylindrical with a diameter of 2.5 cm and length of 15 cm. The resistor has a uniform temperature of $90^\circ C$ and the room air temperature is $20^\circ C.$ Assuming that heat transfer by radiation is negligible, determine the heat transfer coefficient by convection.

Evaluate the Prandtl number from the following data: $c_{p}=0.5 \mathrm{B} \mathrm{tu} / \mathrm{lbm} \cdot \mathrm{R}, k=2 \mathrm{Btu} / \mathrm{h} \cdot \mathrm{ft} \cdot \mathrm{R}, \mu=0.3 \mathrm{lbm} / \mathrm{ft} \cdot \mathrm{s}$

Consider a house in Atlanta, Georgia, that is maintained at $22^\circ C$ and has a total of $20m^2$ of window area. The windows are double-door type with wood frames and metal spacers and have a U-factor of $2.5 W/m^2 \cdot K$. The winter average temperature of Atlanta is $11.3^\circ C.$ Determine the average rate of heat loss through the windows in winter.

A spherical interplanetary probe with a diameter of 2 m is sent out into the solar system. The probe surface is made of material having an emissivity of 0.9 and an absorptivity of 0.1. Signals from the sensors monitoring the probe surface temperatures are indicating an average value of $-40^{\circ} \mathrm{C}$ for a space temperature of $0 \mathrm{~K}$. If the electronics inside the probe are generating heat at a rate of $100 \mathrm{~W} / \mathrm{m}^3$, determine the incident radiation rate on the probe surface.

Two surfaces, one highly polished and the other heavily oxidized, are found to be emitting the same amount of energy per unit area. The highly polished surface has an emissivity of 0.1 at $1070^\circ C,$ while the emissivity of the heavily oxidized surface is 0.78. Determine the temperature of the heavily oxidized surface.

An electric current of 5 A passing through a resistor has a measured voltage of 6V across the resistor. The resistor is cylindrical with a diameter of 2.5 cm and length of 15 cm, The resistor has a uniform temperature of $90^\circ C$ and the room air temperature is $20^\circ C.$ Assuming that heat transfer by radiation is negligible, determine the heat transfer coefficient by convection.

A transistor with a height of 0.4 cm and a diameter of 0.6 cm is mounted on a circuit board. The transistor is cooled by air flowing over it with an average heat transfer coefficient of $30W/m^2 \cdot K.$ If the air temperature is $55^\circ C$ and the transistor case temperature is not to exceed $70^\circ C.$ determine the amount of power this transistor can dissipate safely. Disregard any heat transfer from the transistor base.

A rocket sled has the following equation of motion: . How long must the rocket fire before the sled travels 2000 m? The sled starts from rest.

Consider a sealed 20-cm-high electronic box whose base dimensions are 50cm × 50 cm placed in a vacuum chamber. The emissivity of the outer surface of the box is 0.95. If the electronic components in the box dissipate a total of 120 W of power and the outer surface temperature of the box is not to exceed $55^\circ C,$ determine the temperature at which the surrounding surfaces must be kept if this box is to be cooled by radiation alone. Assume the heat transfer from the bottom surface of the box to the stand to be negligible.

Air at $20^\circ C$ with a convection heat transfer coefficient of $20 W/m^2 \cdot K$ blows over a pond. The surface temperature of the pond is at $40^\circ C.$ Determine the heat flux between the surface of the pond and the air.

The inner and outer surfaces of a 25-cm-thick wall in summer are at $27^\circ C$ and $44^\circ C,$ respectively. The outer surface of the wall exchanges heat by radiation with surrounding surfaces at $40^\circ C,$ and convection with ambient air also at $40^\circ C$ with a convection heat transfer coefficient of $8W/m^2 \cdot K.$ Solar radiation is incident on the surface at a rate of $150 W/m^2.$ If both the emissivity and the solar absorptivity of the outer surface are 0.8, determine the effective thermal conductivity of the wall.

A gun is aimed at a point A located $35^{\circ}$ east of north. Knowing that the barrel of the gun forms an angle of $40^{\circ}$ with the horizontal and that the maximum recoil force is 400 N, determine (a) the x, y, and z components of that force, (b) the values of the angles $\theta x$, $\theta y$, and $\theta z$ defining the direction of the recoil force. (Assume that the x, y, and z axes are directed, respectively, east, up, and south.)

In a power plant, pipes transporting superheated vapor are very common. Superheated vapor is flowing at a rate of 0.3J kg/s inside a pipe with 5cm in diameter and 10m in length. The pipe is located in a power plant at $20^\circ C,$ and has a uniform pipe surface temperature of $100^\circ C.$ If the temperature drop between the inlet and exit of the pipe is $30^\circ C,$ and the specific heat of the vapor is $2190 J/kg \cdot K,$ determine the heat transfer coefficient as a result of convection between the pipe surface and the surrounding.