Intermediate physics / by W. Watson.

  • Watson, W. (William), 1868-1919.
Date:
1912
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Licence: In copyright

Credit: Intermediate physics / by W. Watson. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    3. If the density of ice is -917 and that of sea-water 1*025, what fraction of the volume of an iceberg is above Avater ? 4. A uniform thin cylinder consisting of a length of 20 in. of wood of which the specific gravity is 75, and half an inch of metal of which the specific gravity is 6, is floated upright in water ; how much of the cylinder will be above the surface ? 5. In the above example will the cylinder when floating upright be in stable equilibrium, and where approximately Avill the metacentre be situated ? 6. Show how to find the resultant pressure of a heavy liquid on an immersed body. A block of wood 6 ft. square and 1 ft. thick is floating in sea-water of which the specific gravity is 1-025. If the specific gravity of the wood is 0*6, what weiglit of iron can be placed on the block without it being entirely immersed ? 7. In what proportion should two liquids, A and B, be mixed so that the mixture may have a density of 1'4, the density of A being '9 and that of B 1-6 ? 8. Find an expression for the velocity of efflux of water through a circular hole in the bottom of a vessel, the head of water in the vessel being kept constant. 9. What is meant by the surface tension of a liquid ? Calculate the height to which a liquid will rise in a capillary tube. How would your calculation be affected by a want of uniformity in the bore of the tube ? 10. Show that the energy of a soap film is equal to 2T per sq. cm. where T is the surface tension of the liquid. How much work against surface tension has to be performed to blow a soap-bubble 10 cm. in diameter if the surface tension of soap solution is 49 dynes per cm. 11. Two vertical parallel glass plates, 0*2 of a millimetre apart, are immersed in water for which the surface tension is 80 dynes per cm., the angle of con- tact being 0°. Find the height to which the water will rise at some distance from the edges of the plates. 12. Explain what is meant by Young's modulus. If Young's modulus for a steel wire is 2x10^^ dynes/cm.2, what weight must be suspended from a wire 2 metres long and 1 mm. in diameter to stretch it by 1 mm. ? ((7 = 980 cm./sec.^.) 13. Explain how Young's modulus for a material may be deduced by obser%dng the extension of a wire. Draw the stress-strain diagram for this case, and show how the work performed in straining the wire can be obtained from such a diagram. 14. A uniform tube of length L, filled with air at atmospheric pressure, of which the upper end is closed, is lowered mouth downwards in water. Show that it' H is the height of a water barometer, and the water rises in the tube through a distance x, then the depth D to wdiich the tube has been lowered is given 15. An open trough of which the vertical cross-section is a square, each side 50 cm., is filled with water. One of the vertical ends of the trough is hinged at its upper edge. Find the least force which applied to this end will keep it closed. BOOK II CHAPTEE I 1. A glass rod when measured with a zinc scale, both being at 20° C, appears to be a metre long. If the scale is correct at 0° C, what is the true length of the glass rod at 0° ? The coefficient of linear expansion of glass is 0-000008, and that of zinc O'OOOOS. 2. A barometer with a glass scale reads 760 mm. at 17° C. Find the correction required to reduce the readings to 0° C, if the apparent coefficient of expansion of mercury in glass is '0001558, and the coefficient of linear expansion of glass is -0000087. 3. Describe an absolute method of determining the expansion of mercury with rise of temperature. Knowing the expansion of mercury, describe exactly how you would find the expansion of another liquid between 0° and 100° C.