How to Calculate the Mass of an Object

Two Methods:Using a Triple-Beam BalanceUsing the Density and Volume

Calculating the mass of an object is a necessary step in many science experiments and math problems. Without guidance it may seem impossible, but with these simple steps it'll be easy as pi.

Method 1
Using a Triple-Beam Balance

  1. Image titled Calculate the Mass of an Object Step 1
    1
    Set up the balance. Make sure the pan you will place your object onto is clean and dry.
  2. Image titled Calculate the Mass of an Object Step 2
    2
    Zero the balance. Move all the weights to the zero position, then turn the knob on the far left beneath the scale pan. The scales should move around. Continue turning it in either direction until the white "pointer" line on the right of the beams lines up with the "0" marking on the right-hand side.
  3. Image titled Calculate the Mass of an Object Step 3
    3
    Place the object in the pan. Be careful not to influence the weight of the object with your hand or other objects.
  4. Image titled Calculate the Mass of an Object Step 4
    4
    Move the weights. Slide the weights left and right on the beams until the two white lines at the right line up again. The most efficient way to do this is to make a rough estimate as to what you think the mass will be, and then move the highest value weight you think will still be lower than the mass. Move this weight until the pointer is just under 0. Then move on progressively to the next smallest weights to get closer and closer to the actual mass.
  5. Image titled Calculate the Mass of an Object Step 5
    5
    Read the mass. Add the measurement of each weight together. The total will be the mass of the object.

Method 2
Using the Density and Volume

  1. Image titled Calculate the Mass of an Object Step 6
    1
    Know the equation. The set equation relating mass, density, and volume is D=m/v or density equals mass divided by volume.
  2. Image titled Calculate the Mass of an Object Step 7
    2
    Plug your values into the equation. If the density of your object is 500 kg/m3 (kilograms per cubic meter), then you put 500 in place of the D for 500=m/v. If your volume is 10 m3 (cubic meters), put 10 in place of the v for 500=m/10.
  3. Image titled Calculate the Mass of an Object Step 8
    3
    Isolate the variable. As you are trying to calculate mass, the variable in this equation is m. You want this value to end up alone on one side of the equal sign. In this equation, it is involved in division with another value. To isolate it, you must multiply both sides of the equation by this value. This equation becomes (500)10=(m/10)10.
    • Isolating a variable is always done by performing the opposite mathematical function on both sides of an equation. If the variable is involved in addition, subtract the extra value from both sides, etc.
  4. Image titled Calculate the Mass of an Object Step 9
    4
    Simplify. On the left side of the equation, 500 times 10 simplifies to 5000. On the right side, the two 10's cancel out, leaving the m alone. Thus the answer is 5000kg=m.
    • Don't forget your units. The cubic meters have canceled each other out to leave only kilograms.

Things You'll Need

  • Triple-beam balance
  • Calculator or paper and pen

Tips

  • If you know the density but not the volume, you can find the volume of an irregularly shaped object by filling a graduated cylinder with a known amount of water that will completely cover the object, then inserting the object. The change in volume will be the volume of the object.

Article Info

Categories: Mathematics