ASSIGNMENT 3 Essay Example

. 3A dam wall as shown in figure has water to a depth of 8 m behind it. The wall is 15 m long. Calculate the force on the wall and the overturning moment about the base. The density of water is 1000 kg/m


The dam has a rectangular shape with a width, w. The surface area at the top edge is as follows:


ASSIGNMENT 3 3 moment of area about the top surf ace = st1

ASSIGNMENT 3 4 moment of area about the top surface =nd2

This shows that the centre of pressure is h/3 from the bottomASSIGNMENT 3 5

The total force is given by the following:


The overturning moment about the base is given by:


A steel bar of length 0.25 m and diameter 30 mm is suspended on a chain and lowered into a tank of oil. If the relative density of the oil is 0.86 determine

  1. The up-thrust on the bar

Volume of the steel bar,



ASSIGNMENT 3 10Up-thrust =

  1. The tension in the chain when the bar is fully immersed.

3Density of water is 1000 kg/m

3Density of the steel is 7870 kg/m

Weight of steel = D x V =7870 x 0.177=1392.99N

The tension in the chain = 1392.99 – 1389.096 = 3.894N

(Muncaster, 2003)

The velocity of 0.05 m/s in a duct is increased through a gradually tapering pipe to 2.5 m/s.

. 2 and u2 respectively and at the output be A1 and u1Let the cross sectional area and velocity at the input be A

2u2=A1u1The quantity of the fluid displaced = A



Thus, the ratio between the input and output diameter is given by the following


that might be used to determine the density of a solid material and the density of a liquid. You should research several methods and compare them for accuracy. Your answer should indicate an in depth understanding of the methods.methods the Evaluate

The density of a sample can be obtained directly from the ratio of its known mass and volume from the following equation.

Density = mass/volume

. Koleske, 2012) This is the simplest, quickest method for measuring density. The method utilise the principle that the density of a liquid varies depending on the depth of the immersed body floating on it. The sample is placed in a specific cylinder. A hydrometer is then lowered into the sample and allowed to float freely. The hydrometer is read when they reach the same temperature, when the graduation scale is nearest to the apparent intersection of the horizontal plane surface of the liquid (Hydrometer method —

. Koleske, 2012)this method can be used to measure both the solid and liquid sample. It is more precise and accurate compared to hydrometer method. Pycnometer is first filled with water and weighed, before filling it with the sample and weighed. The relative density or density of the sample is calculated from the weight of the sample and the weight of water required to fill the pycnometer (Pycnometer method –

. Koleske, 2012) this is a rapid, instrumental, direct reading method used to measure the density of a sample using a digital density meter. A small amount of sample is introduced into a vibrating quartz tube in the instrument at a specific temperature. The instrument works of the principle that the quartz tube oscillation is damped depending on the function of the density of the sample. The density of the sample is read out from the instrument (Digital density meter –


. West Conshohocken, PA: ASTM International.Paint and coating testing manual: Fifteenth edition of the Gardner-Sward handbookKoleske, J. V. (2012).

. Cheltenham: Thornes. A-level physicsMuncaster, R. (2003).

. Hagerstown, MD: Wolters Kluwer Health/Lippincott Williams and Wilkins.Dynamic and static parameters of fluid responsivenessSubramaniam, B., & Park, K. W. (2010).