Word Problems Using Significant Figures

Rule:  When calculating the number of significant figures allowed in an answer, the following categories are NOT considered:

example: 25 students, each carrying 2.693 54 kg of sugar

à 25 x 2.693 54 kg = 67.338 5 kg

example: volume of a sphere = 4/3 p r³    for sphere with radius 2.11111 cm

à 4/3 p 2.11111³ = 39.4114 cm³    (using 3.141 6 for p)

1 km = 1000 m    the 1 is considered to have several significant figures

Sample problems:  (not found in other practice problem sheets)

1.  What is the perimeter of a rectangle with a length of 2.1 m and a width of 0.65 m?

          P = 2l + 2w

2.  The period of an oscillating spring is T = 2pÖ(m/k).    If the spring constant (k) is

0.9531 N/m and the mass (m) is 1.2 kg, what is the period?

3.  How long does it take light traveling at 2.99793 E 8  m/s to travel across a room that is

6.2 m long?

4.  The 100 sheets of a textbook measure 0.02375 m.  What is the thickness of only 1 of those sheets?

5. The period of revolution for Uranus is 30 685.93 days.  How many hours is that?

6.  If the thickness of 1 sheet of paper is 0.023 7 cm, what is the thickness of 6 of those sheets?

7.  The perimeter of a polygon is the sum of its sides.  What is the perimeter of a polygon with sides of 25.623 m, 5.97 m, 3.21 m, 0.2 m, and 4.621 m?

8.  The circumference of an ellipse = 2pÖ((a² + b²)/2)    (p = 3.1416)     What is the circumference of an ellipse that has a semi-major axis (a) of 6.987654 m and a semi-minor axis (b) of 2 m?

Answers available from Mr. Jones