Density & Percent Error

Ever wonder how wrong your measurements might be? Percent error tells you exactly that! It shows how far your experimental value differs from the accepted value using the formula:

% error = |Observed Value - True Value| ÷ True Value × 100

For example, if you measure a book as 16.55 cm when it's actually 18.00 cm, your percent error would be |16.55 - 18.00| ÷ 18.00 × 100 = 8.05%. This means your measurement was off by about 8%.

Density measures how much matter is packed into a given space. It's calculated using D = M/V (mass divided by volume). Remember, changing an object's size or shape doesn't affect its density because both mass and volume change proportionally.

Science Tip: Temperature and pressure can affect density! When temperature increases, volume increases while mass stays the same, so density decreases. For gases, increased pressure reduces volume, which increases density.

Measuring density requires finding both mass (using a triple beam balance) and volume. For regular objects, use geometric formulas $V = l × w × h$. For irregular objects, use the water displacement method by measuring the water level change when the object is submerged.