Measuring

Mass

using the

Metric SystemAlice L. Comisky

MASS

Definition: Mass is the amount of matter in an object.

Tools: triple beam balance

Unit of measure: gram-used in science class

The most common tool used in science class for measuring mass in the metric system is the triple beam balance. The mass of an object can be found to the nearest tenth of a gram using this tool.

Base

Adjustment Knob

Pan

Upright

PointerZero

Take the time to learn the names for the parts of the triple beam balance.

The back or 100-gram, beam is divided into ten units of 10 grams each.

The middle, or 500-gram, beam is divided into five units of 100 grams each.

The front, or 10 gram, beam is divided into ten major units of 1 gram each. Each of these units is further divided into units of 0.1 gram.

Before using the triple beam balance make sure all three riders read zero and the pointer is at zero.

If the pointer is not at zero turn the adjustment screw under the pan until the pointer is at zero.

Helpful Hint:Helpful Hint: On most balances turning the knob towards you will move the pointer down. Turning the knob away from you will move the pointer up.

Zero the balance

When the pointer is at zero your balance is ready to use.

What steps must you take if your pointer is not at zero?

Turn the adjustment screw under the pan until you bring the pointer to zero.

Following the steps on the next 9 pages you will learn how to use the triple beam balance to find the mass of a solid, a powder and a liquid.

1. Zero the balance

2. Place the object on the pan

3. Move the rider on the middle beam notch by notch until the pointer drops below zero. Move the rider Back one notch.

4. Move the rider on the back beam notch by notch until the pointer again drop below zero. Move the rider BACK one notch.

5. Slowly move the rider along the front beam until the pointer stops at the zero mark.

6. The mass of the object is equal to the sum of the readings on all three riders.

**Finding the Mass of a Solid**

What mass is shown by the riders on this triple beam balance?

455.7 g

What mass is shown by the riders on this triple beam balance?

322.0 g

1. Zero the balance

2. Place a mass boat (or a sheet of filter paper) on the pan. Find the mass of the mass boat. Record the mass.

Finding the Mass of a Powder

filter paper weighing pan

the mass of this mass boat is 1.9 g

3. Place the powder in the mass boat. NEVER place the powder directly on the pan.

4. Find the mass of the mass boat and powder.

Finding the Mass of a Powder

5. Record the mass of the mass boat and powder.

6. Subtract the mass of the mass boat from the combined mass of the mass boat and powder. The result is the mass of the powder.

Finding the Mass of a Powder

The combined mass of the mass boat and the powder is 103.4 g.

103.4g combined mass

- 1.9g mass of mass boat

101.5 g mass of the powder

1. Zero the balance

2. Place a beaker on the balance pan. Find the mass of the beaker. Record the mass.

**Finding the Mass of a Liquid**

The mass of the beaker is 51.1g

3. Pour the liquid into the beaker and find the combined mass of the liquid and the beaker.

Finding the Mass of a Liquid

The combined mass is 93.2g.

4. Subtract the mass of the beaker from the combined mass of the beaker and liquid. The result is the mass of the liquid.

Finding the Mass of a Liquid

93.2 g combined mass of beaker and liquid

51.1 g mass of the beaker

42.1 g mass of the liquid

Review this presentation and take the time to practice using the triple beam balance.

Alice L. Comisky