2 Chapter Two: Science Skills 2.1 Mass and Volume2.2 Density2.3 Graphing2.4 Solving Problems
3 Section 2.1 Learning Goals Explain the meaning of mass and describe the units for measuring mass.Distinguish between mass and weight.Define volume and explain how the volume of matter is measured.
4 Measuring Mass and Volume Investigation 2AMeasuring Mass and VolumeKey Question:How do you measure mass and volume?
5 2.1 Measuring mass Mass describes the amount of matter in an object. The SI unit for mass is the kilogram (kg).The kilogram is too large a unit to be convenient for small masses.Bananas = 1000 gCat = 5000 gPerson = 55000Motorcycle = 200,000One gram (g) is one-thousandth of a kilogram.What is the estimated mass of ONE zinc nut?
6 2.1 Matter Matter is anything that has mass and takes up space. All matter has mass.Steel, plastic, rubber, and glass are different kinds of matter.Bananas = 1000 gCat = 5000 gPerson = 55000Motorcycle = 200,000A car has a lot more of each kind of matter than a bike.
8 2.1 Mass and weight are different We tend to use the terms mass and weight interchangeably, but they are not the same thing.Mass is the amount of matter in an object.Weight is a measure of the pulling force of gravity on an object.
9 2.1 Mass and weight are different A 2.3 kg bag of flour has a mass of 2.3 kilograms no matter where it is in the universe.The weight of the bag of flour is less on the moon.The 5 lb bag of flour on Earth weighs only .8 lbs on the moon!
11 2.1 VolumeVolume is the amount of space an object takes up.The fundamental unit of volume in SI is the cubic meter (m3).More convenient smaller units are cubic centimeters (cc or cm3), liters (L) and milliliters (mL).
12 2.1 Volume Measuring the volume of liquids is easy. Pour the liquid into a graduated cylinder and read the meniscus at eye level.
13 2.1 DisplacementYou can find the volume of an irregular shape using a technique called displacement.Put the irregularly shaped object in water and measuring the amount of water displaced.
14 2.1 Comparing mass and volume Mass and volume are two different properties of matter.Size does not always indicate an object’s mass!How the matter is packed into space is more important.
15 Chapter Two: Science Skills 2.1 Mass and Volume2.2 Density2.3 Graphing2.4 Solving Problems
16 Section 2.2 Learning Goals Define density in terms of mass and volume.Identify units used to express the density of materials.Apply the density formula to solve problems.
17 Density Investigation 2B Key Question: How is an object’s density related to its volume, mass, and tendency to sink or float?
18 2.2 DensityDensity describes how much mass is in a given volume of a material.
23 2.2 Density of common materials Density is a property of material independent of quantity or shape.
24 2.2 Density of common materials Liquids tend to be less dense than solids of the same material.Ex. solder (“sodder)
25 2.2 Density of common materials Water is an exception to this rule.The density of solid water (ice) is less than the density of liquid water.
26 2.2 Determining DensityTo find the density of a material, you need to know the mass and volume of a solid sample of the material.Mass is measured with a balance or scale.Use the displacement method or calculate the volume.
27 2.2 Density Density changes for different substances because: Atoms have different masses.Atoms may be “packed” tightly or loosely.
38 2.3 How to make an XY graphScatterplots show how a change in one variable influences another variable.The independent variable is the variable you believe might influence another variable.The dependent variable is the variable that you hope will change as a result of the experiment.
39 2.3 How to make an XY graph Pressure is critical to safe diving. How does an increase in depth affect the pressure?What sort of graph would best show the relationship between pressure and depth?
40 2.3 How to make an XY graph Choose x and y-axis Make a scale Depth is the independent variable = x axisPressure is the dependent variable = y axisMake a scaleMost graphs use ones, twos, fives or tensOR calculate the value per boxPlot your dataCreate a title* Exception- when time is a variable
46 2.3 Reading a graph What is the speed of the car at 50 cm? Find the known value on the x axisPosition = 50 cmDraw a line vertically upward from 50 cm until it hits the curve.Draw a line across horizontally to the y- axis from the same place on the curve.Read the speed using the y axis scale.Speed = 76 cm/s
47 Chapter Two: Science Skills 2.1 Mass and Volume2.2 Density2.3 Graphing2.4 Solving Problems
48 Section 2.4 Learning Goals Apply a four-step technique to solve problems.Use the design cycle to solve problems.
51 Calculate marble’s volume & density Looking for: Givens: Solving ProblemsCalculate marble’s volume & densityLooking for:volume, then densityGivens:mass = 6 g , water displaced 30 to 32 mLRelationships:water displaced = marble volume, D = m/VSolution:32 mL – 30 mL = 2 mLD = 6 g / 2 mL= 3 g/mL
52 2.4 How to solve design problems Use what you know to design a solution that solves the problem.Unlike “formula problems,” design problems have many correct solutions.The solutions are only limited by your creativity, ingenuity, skill, and patience.
53 2.4 How to solve design problems What does your design need to accomplish?What constraints do you have?Think of an idea.Follow the design cycle…
54 Density and Ocean Currents Did you know that there are underwater waterfalls in the ocean?While it may seem strange for water to fall through water, it really happens due to density differences in ocean water coming from different sources.