m30973 Mass 1.1 2009/08/03 07:42:12.186 GMT-5 2009/08/03 07:52:20.303 GMT-5 gert bezuidenhout gert bezuidenhout gertb@mweb.co.za gert bezuidenhout gert bezuidenhout gertb@mweb.co.za gert bezuidenhout gert bezuidenhout gertb@mweb.co.za Mathematics and Statistics en

1. As in length, it is essential that we know when to use grams, kilograms and tons as units. Work with a friend, taking turns. Take any three objects in your class. Hold each one separately and arrange them from the lightest to the heaviest. In which unit would you weigh these items: grams? kg?; ton? Complete the table: Item From light to heavy Unit 1. .......................................... .......................................... .......................................... 2. .......................................... .......................................... .......................................... 3. .......................................... .......................................... .......................................... DO YOU STILL REMEMBER? 1 000 g = 1 kg 1 000 kg = 1 ton Sometimes an object can be so light that you can’t weigh it on a normal scale. Tick the objects that you think weigh less than 1 gram. a feather a rubber a pin a staple an orange a grain of sand a hair elastic a pen a hair

DID YOU KNOW? When we want to determine the mass of an object, it means that we want to know how heavy it is or how much it weighs. To be able to do this, we need a scale. Please write down all the different kinds of scales you can think of: Study the following scales carefully. Work with a friend and write down the reading of each scale. 1.1

1.2

1.3

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1.6

2. Kyk na die volgende tekeninge en skryf die massa van die voorwerpe neer. 2. Look at the following drawings and write down the mass of each object: 2.1

2.2

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Work in groups of three. Bring the following items from home: A scale; 1 cup of raw rice; 1 cup of sugar; 1 cup of flour; 1 cup of salt; 1 cup of all bran/corn flakes and 1 cup of raisins.(Remember to use the same cup each time you measure). 1. Determine the mass of each item and complete the table. Item Mass in g estimated Item weighed Difference .............................................. ......................... ..................... ..................... .............................................. ......................... ..................... ..................... .............................................. ......................... ..................... ..................... .............................................. ......................... ..................... ..................... .............................................. ......................... ..................... ..................... .............................................. ......................... ..................... ..................... 2. Which item is the heaviest? 3. Which item is the lightest?

LET US REVISE! How will we write the grams in the table above as kg? I know 1 000 g = 1 kg Thus: 1 g = 11000 size 12{ { { size 8{1} } over { size 8{1`"000"} } } } {}kg= 0,001 kg In the same way 17 g will be 17 thousandths of a kg. 17 g = 0,017 kg and 234 g = 0,234 kg 4 387 g = 4 kg 387 g = 4,387 kg 1. Write the following as kg. a) 9 g ............................ b) 26 g ............................ c) 89 g ............................ d) 436 g ............................ e) 2 309 g ............................ f) 5 006 g ............................

2. Study the different weight pieces below. Choose the fewest number of weights you will need to balance the scale and write them down. Mass Weights needed e.g. 1,010 kg 1 kg ; 10 g 1,023 kg .................................................................................................... 1,023 kg .................................................................................................... 1,007 kg .................................................................................................... 1,056 kg .................................................................................................... 983 g .................................................................................................... 724 g .................................................................................................... 4. Rounding off 4.1 Can you round off the following to the nearest kg? (a) 7,6 kg ......................... (b) 0,5 kg ......................... (c) 4,2 kg ......................... (d) 2,5 kg ......................... 4.2 Round off the following to the nearest ton: (a) 20,8 t ......................... (b) 29,4 t ......................... (c) 1,5 t ......................... (d) 34,9 t ......................... BRAIN-TEASER! You want to determine the mass of a chair. You have a bathroom scale, but the chair is too big for it and falls off. How can you determine the mass of the chair without using a bigger scale?

LO 4 MeasurementThe learner will be able to use appropriate measuring units, instruments and formulae in a variety of contexts. We know this when the learner: 4.1 reads, tells and writes analogue, digital and 24-hour time to at least the nearest minute and second; 4.2 solves problems involving calculation and conversion between appropriate time units including decades, centuries and millennia; 4.3 uses time-measuring instruments to appropriate levels of precision including watches and stopwatches; 4.4 describes and illustrates ways of representing time in different cultures throughout history; 4.5 estimates, measures, records, compares and orders two-dimensional shapes and three-dimensional objects using S.I. units with appropriate precision for:mass using grams (g) en kilograms (kg);capacity using millimetres (mm), centimetres (cm), metres (m) en kilometres (km);length using. millimetres (mm), centimetres (cm), metres (m) en kilometres (km); 4.6 solves problems involving selecting, calculating with and converting between appropriate S.I. units listed above, integrating appropriate contexts for Technology and Natural Sciences; 4.7 uses appropriate measuring instruments (with understanding of their limitations) to appropriate levels of precision including:bathroom scales, kitchen scales and balances to measure mass;measuring jugs to measure capacity;rulers, metre sticks, tape measures and trundle wheels to measure length.

ACTIVITY 1 √ √ √ √ √ ACTIVITY 2 Bathroom scale; spring balance; kitchen scale; balance/scale 1. 1.1: 6,25 kg 1.2: 88,5 kg 1.3: 3 kg 1.4: 17,68 kg 1.5: 210 g 1.6: 172 kg 2. 2.1: 3,050 kg 2.2: 5,710 kg 2.3: 1,215 kg 2.4: 0,604 kg ACTIVITY 4 1. 1.1: 0,009 1.2: 0,026 1.3: 0,089 1.4 0,436 1.5 2,309 1.6 5,006 3. MASS PIECES NEEDED 1 kg; 20 g; 2 g; 1 g 1 kg; 20 g; 5 g; 2 g; 1 g 1 kg; 5 g; 2 g 1 kg; 50 g; 5 g; 1 g 20 g; 10 g; 2 g; 1 g500 g; 200 g; 200 g; 50 g 500 g; 200 g; 20 g; 2 g; 2 g 4. 4.1 a) 8 b) 1 c) 4 d) 3 4.2 a) 21 b) 29 c) 2 d) 35 BRAIN-TEASER! Stand on scale and take the reading; then hold chair above your head while on the scale and take reading again (or vive versa); the difference in the readings is the mass of the chair.