Analysis of the poem “Let America Be America Again” by Langston Hughes


Ability of three different materials to absorb energy


The essence of this experiment was to familiarize ourselves with one impact test type and the ability of three different materials to absorb energy. The materials include; aluminium alloy (2024-T4), A36 steel and an alloy steel (4140). The materials were each tested under a vast variety of temperatures using the standard Impact machine. The deviations in temperature, are essential in facilitating observation of changes in both rigidity and strength of the materials by the tester. Ideally, the levels of strength and toughness are directly proportional to the levels of temperature.

Introduction/ Experimental setup:

The objective of this lab test is to find the impacts of temperature on the breakage energy of various metals. The procedure is first begun by preparing different liquid baths to certain expected temperature levels. The liquids in this case are; liquid nitrogen, dry ice with  little traces of acetone, dry ice with copious amounts of acetone, normal ice in salty water, ice, boiling, warm and tap water. 8 specimens of 3 the different metals are also required. The specimens should be in the following dimensions; 2.16 x 0.375 x 0.375 inches, and a radius of 0.01 inches in an angle of 45 degrees at the centre of the longest side of the specimen.

To carry out the experiment, each of the specimens should be first soaked in the corresponding bath for a roughly 10 minutes, the point at which the exact temperature of the bath is determined using a thermocouple. The specimens are then supposed to be extracted from the bath, after which they are put with the notch within 10 seconds facing forward in the charpy Impact test machine. At this point, the energy that fractures the different specimens is recorded. It is however important to note that, before testing each specimen, it is essential to ascertain that the pointer on the Charpy tester is at zero and does not move in the process of the test. In addition, the brake of the Charpy machine should not be on before the test procedure.

The respective temperatures for the different baths ad their respective impact energy are then recorded. A graph should then be plotted using the results for each material for the fracture energy against the temperature.


  1. In the test, the A36 steel was found to fracture in temperature ranges between -300 and -100 degrees, the point after which the material was found to show different reactions. Some of the reactions were; long grain-like particles at the pointed protrusion towards the direction in which force was exerted by the striking hammer. After the 3 samples snapped, it seemed to break along the natural planes of weakness of the material and the two sides of the material were actually smooth. The materials were found to fracture less often in higher temperature levels and exhibited higher strength as pertains the stretching of the grains sidewise and following smaller angular planes of bending.
  2. Toughness is usually expressed as the amounts of energy absorbed by a material before it snaps/fractures. It is normally determined by getting the area of the lower region of a graph curve plotted of the material’s stress against the strain. Strength refers to the levels of stress a material can withstand before snapping. Brittle materials are normally thought to possess higher strength. However, they are less useful due to their low toughness and thus, are susceptible to fracturing under other certain conditions, such as; applying a load that can otherwise deform its structure.
  3. The initial kinetic energy and the final potential energy can be determined using the conservation of energy theory. In our case, the initial K.E is 0 since the hammer was initially stationary while the final P.E is also 0 since the sample is used as the reference point to itself.Ability of three different materials to absorb energy


PE (initial) = KE(final) or

Mgh = ½ mv ^2


Whereby the following are given;

m=45 lb,          h=32 in            g=32.2 ft/s^2


As such, calculating V would give us 13.1 ft/s

Ability of three different materials to absorb energy

  1. The area in proximity to the notch, contracts while the farthest side from the notch does expand from the direction towards which the force is imparted. The specimen when hit from the back by the hammer, experiences a sudden bending and at the same time, the side on which the force is imparted expands while the opposite side contracts.

Ability of three different materials to absorb energy


The impact test is a clear indication of how the given materials react to different temperature variations. In the case of A36 and alloy steel, they increase in their malleability and toughness since they are able to absorb more energy in higher levels of temperature as compared to lower levels. Aluminium alloy on the other hand, is brittle because of its capability to absorb almost the same energy levels regardless of the temperatures. Ductility and toughness are important properties of a material and thus, must be known prior to using materials in whatever situation.