myphysics6.docx - OpenStudy

Document Sample
myphysics6.docx - OpenStudy Powered By Docstoc
					Need answer to this question on Thermal expansion II so that i can compare my solutions to
yours;
How many grams of mercury have to be enclosed in a thermometer at 0 °C, to show a change of the
mercury column of 1.0 mm for an increase of 1.0 K, assuming it has a capillary diameter of 0.50 mm.
Use: density Hg = 13.546 g/cm 3, ßHg = 0.182 ·10-3 K-1, glass = 9.0 ·10-6 K-1

Need answer to this question on Heat of transformation and heat capacity so that i can
compare my solutions to yours;

a) How much water evaporates during the quenching of a red-hot piece of iron (12 kg at 700 °C) when
dipped in water (5.0 kg at 20 °C) which is filled i n an iron tank of 2.0 kg.
Use: heat of evaporation of water of 2257 kJ/kg, and specific heat of iron of 0.45 kJ/(kg K) and that of
water of 4.19 kJ/(kg K).
b) While running a 72 kg student generates thermal heat at a rate of 1200 W. To keep a constant
body temperature of 37 °C, the heat has to be removed by sweating or other mechanisms. Assume
that these mechanisms fail and the student heats up. How long could the student run until irreversible
body damage will occur at a body temperature of about 42 °C? Assume a specific heat of a human
body of 3480 J/(kg K).

Need answer to this question on Thermal expansion so that i can compare my solutions to
yours;
a) A street, 6 m wide, is made of concrete plates which are 6.00 m wide, 12.0 m long and 25.0 cm
thick, and which are, at 20.0 °C, connected by 1.00 cm wide jo intings filled with tar. Calculate the tar
volume oozing out of one jointing at a hot summer day at 35.0 °C.
Use: con = 14.0 ·10-6 K-1, ßtar = 6.00 ·10-5 K-1
b) You drill a hole in an aluminium plate with a steel drill whose diameter at 21.0°C is 6.245 cm.
During drilling, the temperature of the drill bit and the aluminium plate rise to 165 °C. What is the
diamete r of the hole in the aluminium plate when it has been cooled to room temperature?
Use: thermal expansion coefficient of Al of 24.0 10-6 1/K and of steel of 11.0 10-6 1/K

Need answer to this question on Heat conduction so that i can compare my solutions to yours;
a) Calculate the energy loss in watts per square meter through a glass window 4.0 mm thick (thermal
conductivity of glass of 0.80 W/(m K) ) if the outside temperature is - 5.0 °C and the inside
temperature 21°C.
b) Another window consist of two glass plates with the same specifications as in (a) and an air gap of
2.5 cm between the two glass plates (conductivity of air of 0.026 W/(m K)). What is now the rate of
energy loss if conduction is the only important energy loss mechanism?

				
DOCUMENT INFO
Categories:
Tags:
Stats:
views:8
posted:12/5/2011
language:English
pages:1