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PES Skill Sheets.book - Capital High School

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Page 2 of 4<br />

2. The density of titanium is 4.5 g/cm3 . A titanium pendant’s mass is 2.25 grams. Use the formula<br />

Density = ----------------mass<br />

, or D =<br />

m<br />

--- , or to find its volume.<br />

volume v<br />

The Work: What’s happening:<br />

4.5 g × V = (2.25 g) × (1 cm 3 )<br />

Formula<br />

Plug in known values.<br />

Rewrite 4.5 g/cm 3 as<br />

Think of 4.5 g<br />

1 cm<br />

as a proportion.<br />

Then set the cross products equal<br />

3<br />

------------- =<br />

2.25 g<br />

--------------<br />

V<br />

4.5 g × V = 2.25 g × 1 cm 3 Do arithmetic: 2.25 g × 1cm 3 = 2.25 g × 1 cm 3<br />

Check the Work:<br />

In summary:<br />

D<br />

=<br />

m<br />

--v<br />

3<br />

4.5 g/cm =<br />

2.25<br />

-------------g<br />

V<br />

4.5g<br />

1 cm 3<br />

-------------<br />

=<br />

2.25<br />

-------------g<br />

V<br />

4.5<br />

--------------------g<br />

× V 2.25 g 1cm<br />

4.5 g<br />

3<br />

= ----------------------------------<br />

×<br />

4.5 g<br />

Divide both sides of the equation by 4.5 g to get V alone.<br />

V = 0.5 cm 3 Do the division on each side. Remember to cancel units as well as<br />

divide the numbers.<br />

D<br />

=<br />

m<br />

--v<br />

3<br />

4.5 g/cm<br />

2.25 g<br />

0.5 cm 3<br />

=<br />

------------------<br />

Divide 2.25 ÷ 0.5. If the answer is 4.5 g/cm 3 , the solution,<br />

V = 0.5 cm 3 , is correct.<br />

2.25 ÷ 0.5 = 4.5 g/cm 3 The quotient does equal 4.5 g/cm 3 ; therefore, the solution is<br />

correct.<br />

The volume of a titanium pendant whose mass is 2.25 grams is 4.5 g/cm 3 .<br />

4.5 g<br />

1 cm 3<br />

-------------<br />

4.1

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