MEASURING MASS USING A TRIPLE BEAM BALANCE Procedures and Practice (to be used with notes sheet)

What is Mass? Mass is the amount of matter in an object Mass is generally measured in grams or kilograms when using metric units The mass of an object is not affected by gravity but weight is affected by gravity (eg. Your mass would be the same on the moon as it is on Earth, but your weight is less on the moon since the moon has less gravity)

What tool do we use to measure mass? In lab we use a triple beam balance The middle beam measures the largest amounts (100’s of grams), the front beam measures the smallest amounts (0.1’s of grams) and the back beam measures amounts in between (10’s of grams) Each beam has a rider that marks the measurement. To get an object’s total mass, the readings of all three beams are added

PROCEDURES 1. Start with all riders at the zero point with tray empty. 2. Place the object on the tray. 3. Move the largest scale rider until the pointer drops, then move the rider back one notch. Record the number. 4. Move the second largest rider (in back) until the pointer drops, then move the rider back one notch. Record the number. 5. Using a pencil eraser, repeat this for the smallest gram scale. Record the number. 6. Once the balance is balanced, add all three numbers of the riders for the total mass. 7. Remove object from tray and return riders to zero positions.

EXAMPLE: 200 g + 70 g g = ____

NOW YOU TRY Answer the 3 examples on the sheet

What if your object won’t sit on the tray? Sometimes you have to find the mass of an object in a container. Examples: ◦ Sand ◦ Water ◦ Marble ◦ (anything that flows or rolls)

PROCEDURE 1. Find the mass of the container alone. 2. Find the mass of the container plus the object in the container. 3. Subtract the container’s mass from the combined mass.

EXAMPLE: (Beaker alone is 25 g) g (Mass of sand and beaker) g (Mass of beaker alone)