Lab Report 4 1. Aim: . Find the density of a piece of wood and aluminum by determining the volume and weight of each block. . Using Archimedes' principle to find the density of an aluminum block based on its real and apparent weight when the block submerged in water. . Float the wooden block in a water bowl and measuring the height above the waterline to get the density value of the block. 2. Theory: · Archimedes's principle: states that a body immersed in a fluid is subjected to an upwards force equal to the weight of the displaced fluid. · Magnitude of buoyant force: F =pgV + F = Buoyant foce + p = fluid density + g = gravity + V = fluid volume . This force is an upward force, opposing that of the effect of gravity. The buoyant force equation is the same for a totally submerged object of any size, shape, or density. Figure 1:object submerged in fluid Figure 2:object floating on a fluid FB N FB 4 mg mg From the figure 1, the downward force, mg, is greater than the buoyant force so that the object will sink to the bottom.
In figure 2, the buoyant force and weight force are in equilibrium so that the object is able to float on the fluid surface. 3. Theory: . Using the top-pan balance to get the mass of aluminum and wood block. . Using the ruler to determine the volume of the blocks. · Calculating the density of each block by the value of mass divided by its volume. . Using the spring balance to measure the W real of aluminum and W app when the aluminum block is in water. . Make the wood block to float in the bowl of water, measure the height above the waterline and the height of the block. . Calculate the density of the wood floating in the water based on Archimedes' principle. . Hung the aluminum block from the thread and submerged it fully into the water. Get the W2 value. · Calculate the weight difference and compare with the buoyant force got above. 4. Results :
· Experiment 1 Determine the density p (kg . m-3) of the aluminium block and the wooden block using a ruler (for calculating the volume m3) and a top-pan balance (for calculating the mass g) AI 1= 20 mm w = 20 mm ) × 10-3 kg h = 23 mm V = 9.2 ×10 -6 m3 MAL = ( 27.4 PAI =( 2.97 ) × 103 kg · m-3 Wood Mwood = ( 61.2 ) × 10-3 kg I= 60 mm w = 60 mm h = 30 mm V= 1.08 x 10-4 m3 Pwood = ( 0.567 ) × 103 kg · m-3 · Experiment 2 Determine the density p (kg . m-3) of the aluminium block using Archimedes' Principle by measuring the real weight and apparent weight (block submerged) using a spring balance. Wreal =