Laboratory work. Finding the density of a solid
You need: a beam balance with weights, a ruler, rectangular blocks of wood, plastic and metal, small irregular objects (a nut, a key, a coin), water, a measuring cylinder, thread. For a regular body measure length, width and height with a ruler and calculate V = l₁ · l₂ · l₃; find the mass m on the balance; ρ = m : V. For an irregular body first weigh it, then pour into the cylinder enough water that the level will not pass the scale when the body is immersed; write the initial level V₁. Tie the body to a thread and lower it slowly into the cylinder; read the new level V₂; the volume of the body is V = V₂ − V₁ (1 ml = 1 cm³). Write the results in a table and calculate the density, then compare with the table of densities to decide which substance the body is made of.
Laboratory work (in groups): find the density of one rectangular block and one irregular object (a nut); write the results in a table: “body, V₁, V₂, V, m, ρ”. Safety: use a nut or coin instead of sharp objects (scissors, knife); lower the body slowly on a thread so the cylinder does not break and cut hands; wipe up spilled water immediately.