A 50-kg air conditioner is placed on top of a concrete pad that is 20 cm thick and has a cross-sectional area of 3.0 m2. What is the change in thickness of the pad caused by the air conditioner? Young's modulus for concrete is 2.3 × 1010 N/m2
A) 1.4 × 10-9 m
B) 2.8 × 10-9 m
C) 1.4 × 10-8 m
D) 1.4 × 10-7 m
E) 2.8 × 10-8 m
A
You might also like to view...
Light-emitting diodes or LEDs are currently perhaps the most energy-efficient lighting systems. Finned surface heat sinks are used to cool high-intensity LED lighting that are used for spot and/or track lighting systems. A typical circular pin-fin heat sink is shown in the figure, and it is desirable that the fin-base temperature be less than 115°C to ensure efficient performance and longer life of the LED lamp. The fins are made of cold-forged, high-conductivity aluminum (k = 210 W/m K). Each pin has a diameter of 4 mm and a length of 40 mm. If the surrounding air is at 22°C, and it has a convection heat transfer coefficient of ch = 10 W/(m2 K), determine the temperature distribution in the fin, considering convection from the fin tip and the heat transfer rate from the fin. Model it
as a one-dimensional system, use a minimum of 9 nodes (including the ones at the base and tip) or more in your numerical scheme, and determine the effect of extra nodes. Compare the results with the one-dimensional fin analysis of Chapter 2. Also, if 90 such fins are evenly distributed on a 50-mm-diameter circular base, what is the maximum heat transfer rate that is dissipated by this heat sink so that the base temperature is less than 115°C? In a typical LED lamp, approximately 70% of the electric power (or wattage) is dissipated as heat (the remainder 30% is useful light). Determine the maximum power of the lamp, in watts, for which this heat sink is used.
GIVEN
• Light emitting diodes
• Fin base temperature (T0)= 1150C
• Surrounding air temperature (T?)= 220C
• Convection heat transfer coefficient ( ch )= 10 W/(m2 K)
• Thermal conductivity (k)=210 W/(m K)
• Fin diameter (d)= 4 mm = 0.004 m
• Fin length (L)= 40 mm =0.04 m
• Number of nodes (N)=9
FIND (a) Temperature distribution in the fin considering convection from fin tip
(b) Heat transfer rate from the fin.
(c) Maximum heat transfer rate dissipated by 90 such evenly distributed fins
(d) Maximum power of lamp in watts.
SKETCH
Explain what a subduction zone is and how it is related to volcanism
What will be an ideal response?
An ideal gas increases in temperature from 22°C to 42°C by two different processes. In one process, the temperature increases at constant volume, and in the other process the temperature increases at constant pressure
Which of the following statements about this gas are correct? (There may be more than one correct choice.) A) The heat required to cause this temperature change is the same for both the constant-volume and the constant-pressure processes. B) More heat is required for the constant-pressure process than for the constant-volume process. C) The change in the internal (thermal) energy of the gas is the same for both the constant-volume and the constant-pressure processes. D) The root-mean-square (thermal) speed of the gas molecules increases more during the constant-volume process than during the constant-pressure process.
In the SI, weight is expressed in units of ______________
Fill in the blank(s) with correct word