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An exterior wall of a house may be approximated by a 0.1 m layer of
common brick (k = 0.7 W/m°C) followed by a 0.04 m layer of gypsum plaster (k = 0.48 W/m°C).
What thickness of loosely packed rock wool insulation (k = 0.065 W/m°C) should be added to
reduce the heat loss or (gain) through the wall by 80 per cent ?
(AMIE Summer, 1997)
A reactor’s wall 320 mm thick, is made up of an inner layer of fire brick
(k = 0.84 W/m°C) covered with a layer of insulation (k = 0.16 W/m°C). The reactor operates at a
temperature of 1325°C and the ambient temperature is 25°C.
(i) Determine the thickness of fire brick and insulation which gives minimum heat loss.
(ii) Calculate the heat loss presuming that the insulating material has a maximum temperature of 1200°C.
If the calculated heat loss is not acceptable, then state whether addition of another layer of
insulation would provide a satisfactory solution
In a piston-cylinder arrangement, air with a volume of 0.1 m3 and a pressure of 100 kPa is compressed until pv2 = sbt until its pressure reaches 900 kPa. Find the volume of air in the final state and the work done during the process.A bus starts from rest at a station and accelerates at a speed rate of 2m/s^2 for 15 seconds. It then runs at a constant speed for 25 seconds and slows down at -3m/s^2 until it stops. Find the total displacement travelled by the bus
Show that if the temperature on the Celsius scale changes
by TC, the Fahrenheit temperature changes by TF -
(9/5)TC.
A bus driver forgot to stop at a bus stop. Just as he passes the stop, he begins to decelerate 5 seconds later, the bus is 80m beyond the stop and has slowed to 10m/s.
a. Calculate the speed of the bus as it passed the bus stop.
b. What is the deceleration of the bus?
A bus starts from rest at a station and accelerates at a speed rate of 2m/s^2 for 25 seconds. It then runs at a constant speed for 25 seconds and slows down at -3m/s^2 until it stops. Find the total displacement travelled by the bus.
Estimate the number of impacts that air molecules make with the palm of your hand each second, assuming that all air consists entirely of nitrogen (molar mass=0.028kg)?
Find the angle between the two vectors A=2.00i+3.00j+1.00k and B=4.00i+2.00j-1.00k
A block of mass 2 kg is attached to a string that will break if the tension exceeds 500 N. If the block is whirled in a horizontal circle of radius 0.5 m, its maximum speed will be
