2.1 Space and Time 1

Chapter 2 Objectives Express lengths in metric and English units. Convert measurements and calculated quantities between different units. Calculate the surface area and volume of simple shapes and solids. Work with time intervals in hours, minutes, and seconds. Describe two effects you feel every day that are created by mass. Describe the mass of objects in grams and kilograms. Use scientific notation to represent large and small numbers. Design a controlled experiment. Create and use a graphical model based on data.

Chapter 2 Vocabulary element English system experimental variable exponent friction gas graph graphical model independent variable inertia length liquid mass metric system mixture plasma precision procedure scientific notation SI system solid speed surface area time interval variable volume weight x-axis y-axis

Inv 2.1 Distance and Length Investigation Key Question: How do we accurately communicate length and distance? 4

2.1 Space and Time Space in physics means the three dimensions of up-down, left-right, and front-back. The three dimensions of space are described with length units, such as meters, inches, and feet. Time provides another dimension for describing when something occurs.

2.1 Thinking about distance Measurement is a quantity and a unit Distance is the amount of space between two points is measured in units of length

2.1 Two common systems of units Science problem solving requires both: Metric or S.I. system English system

2.1 Two common systems of length Almost all fields of science use metric units. They make calculations easier because the units are based on factors of ten.

2.1 Converting from one unit to another It is often necessary to take a measurement in one unit and convert it into a different unit using conversion factors.

Converting length in yards to meters A football field is 100 yards long. What is this distance expressed in meters? You are asked for the distance in meters (m). You are given the distance in yards (yds). Relationship: 1 yard= 3 feet 100 yds x 3 ft x 0.3048 m = 91.4 m 1 yd 1 ft

2.1 Time Two ways to think about time: What time is it? 11:52 a.m. on March 12, 2010 How much time has passed? 2 hr: 22 min: 42 sec. A quantity of time is often called a time interval.

2.1 How is time measured?

Converting a mixed time to seconds How many seconds are in 1 hour, 26 minutes, and 31.25 seconds? You are asked for time in seconds. You are given a time interval in mixed units. 1 hour = 3,600 sec 1 minute = 60 sec Do the conversion: 1 hour = 3,600 sec 26 minutes = 26 × 60 = 1,560 sec Add all the seconds: t = 3,600 + 1,560 + 31.25 = 5,191.25 sec

2.1 Time scales in physics Events in the universe happen over a huge range of time intervals. In many experiments, you will be observing how things change with time.