## 20140906

### Physics quiz question: linear mass density of paper clip

Physics 205A Quiz 1, fall semester 2014
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 1.19, Comprehensive Problem 1.57(d)

Evaluate the following calculation, using an appropriate number of significant figures and/or decimal places.

1.4 g ÷ 15 cm = ?

(A) 0.09 g/cm.
(B) 0.093 g/cm.
(C) 0.0933 g/cm
(D) 0.09333 g/cm.

Correct answer (highlight to unhide): (B)

1.4 g has two significant figures, while 15 cm also has two significant figures (as denoted in green).

For multiplication and division operations, the term with the least number of significant figures determines the number of significant figures in the result, so the resulting calculation is limited to two significant figures:

1.4 g ÷ 15 cm = 0.09333333333333... g/cm,

and thus the result should be truncated to show only two significant figures, as given by 0.093 g/cm.

Sections 70854, 70855, 73320
Exam code: quiz01w34K
(A) : 28 students
(B) : 45 students
(C) : 1 student
(D) : 0 students

Success level: 61%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.67