4.5 Measuring Matter: Mass, Weight, and Volume

Text pages 113-115

4.5 Overview

Key idea• Explain the concept of force• Determine the density of a

variety of substances

Vocabulary • Mass• Weight• Volume• Meniscus• Displacement

What is matter

• Something that has a mass and volume• If it is not matter… it is energy

What is the difference between mass and weight?

Mass = the amount of matter in an object

– grams, g; milligrams, mg; kilograms, kg– Mass is always the same

Weight= the force of gravity pulling on the object

– Weight is different depending on the planet!– Gravity keeps things on the ground, it is the Earths

pull– The pull of gravity is measured in Newtons, N

If I travelled to the moon, would I lose weight?

• YES, because the moon has a different gravity/pull than on Earth… you are pull down on less on the Moon!

• 9.8 m/s2 = Earths gravitational pull• 1.6 m/s2 = Moons gravitational pull• Your mass will always be the same…. You will always

have the same amount of stuff inside of you!!

Does your bathroom sale measure mass or weight?

• Weight!• It measures the Earth’s pull on your body!

What is Volume

• The amount of “space” that an object takes up = outside

• Capacity= The amount of space in a substance (like a tube, juice container, tube of tooth paste) = inside

• Meters cubed, m3; centimeters cubed, cm3; liters, L; millilitres, mL

Volume is measured in many different ways

• Liquids:– Measured by observing how much of a container they

fill up– Beaker, graduated cylinders (GC), measuring cup– Units = mL, L, kL

• Regular shaped objects (straight edges, cubes, rectangles)– Use a ruler– Volume = L x W x H– Units = m3, cm3

• Small irregular shaped objects (rocks…)– Displacement:• Choose a container that the object can fit in• Fill up with water till half full• Record the volume• Add the object• Record the volume again• Subtract the two volumes = volume of object• This is the amount of space the object took up!

Volume of object = (volume of water + object) – (volume of water)

* larger number * smaller number

• Large irregular shaped objects– Overflow method• Need an overflow can and a GC• Fill overflow can till water starts to come out of spout,

place GC under overflow spout• Add object to over flow container• Record how much water is in the GC• The water that overflowed into the GC = the amount of

space the object took up

Which method is which?

Which method would you use?

If you travelled to the moon, would my volume change?

• NO, you will still take up the same amount of space….