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3 years ago

What is the formula for convection?

1 answer:

8 0

Convection is transfer of heat between a solid and a moving fluid. Boiling or condensing processes are example for convection processes.

The formula for convection is:

q = hc A dT

where

hc is convective heat transfer coefficient of the process (W/(m2K) or W/(m2oC q
A is the heat transfer area of the surface (m2, ft2)
hc = convective heat transfer coefficient of the process (W/(m2K) or W/(m2oC), Btu/(ft2 h oF))q is heat transferred per unit time (W, Btu/hr)dT is the temperature difference between the surface and the bulk fluid (K or oC, F)

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- Thermal Energy Test

timofeeve [1]

Answer:D. The metal in the door expands when it becomes warm due to an increase in kinetic energy, and contracts when it's cooler.

Explanation:

because the metal in the door expands due to warm to an increase in kinetic energy and contracts.

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3 years ago

A 24000- railroad freight car collides with a stationary caboose car. They couple together, and 22 percent of the initial kineti

Klio2033 [76]

Answer:

$m_{c} = 6768\,kg$

Explanation:

According to the Principle of Energy Conservation and the Work-Energy Theorem, the system is modelled as follows:

$K_{o} = K_{f} + W_{loss}$ , where $\frac{K_{f}}{K_{o}} = 0.78$ .

Then,

$K_{f} = 0.78\cdot K_{o}$

$0.5\cdot (m_{f}+m_{c})\cdot v_{f}^{2} = 0.39\cdot m_{f}\cdot v_{o}^{2}$

Besides, the Principle of Momentum Conservation describes the following model:

$m_{f}\cdot v_{o} = (m_{f}+m_{c})\cdot v_{f}$

The final velocity of the system is:

$v_{f} = \frac{m_{f}}{m_{f}+m_{c}}\cdot v_{o}$

After substituting in the energy expression:

$0.5\cdot \frac{m_{f}^{2}}{m_{f}+m_{c}}\cdot v_{o}^{2} = 0.39\cdot m_{f}\cdot v_{o}^{2}$

$0.5\cdot m_{f} = 0.39\cdot (m_{f}+m_{c})$

The mass of the caboose is:

$0.39\cdot m_{c} = 0.11\cdot m_{f}$

$m_{c} = 0.282\cdot m_{f}$

$m_{c} = 0.282\cdot (24000\,kg)$

$m_{c} = 6768\,kg$

8 0

4 years ago

Need help anybody thanks

mars1129 [50]

If there are no windows, then the illumination in the room depends
only on the room and what's in it, not on anything outside.
The time of day has no effect. The other things all do.

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3 years ago

What is the proper function of a linkage? *

Kryger [21]

Answer:

a) transferring energy

Explanation:

A linkage is an assembly of parts connected together to control forces and movement. The connections between links are called joints and are used for ensuring movement, pure rotation or sliding.

Linkages provides a means in which kinetic energy is being transferred in different directions within a system. This Linkages can be used to Change force direction, size of force applied or the motion created by the force.

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3 years ago

A 1.0-kg cue ball traveling at 15 m/s strikes a stationary billiard ball of mass 1.5 kg. After the collision, the cue ball remai

Igoryamba

Answer:

Other ball's velocity is 10 m/s

Explanation:

We can use conservation of momentum:

$P_{1i} +P_{2i} =P_{1i} +P_{2i}\\1 * 15 + 1.5 * 0 = 1 * 0 + 1.5 * v\\15 = 1.5 * v\\v=\frac{15}{1.5} \,\frac{m}{s} \\v=10 \,\frac{m}{s}$

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3 years ago