Physics quiz question: magnitude of vector, given components

Physics 205A Quiz 3, fall semester 2013
Cuesta College, San Luis Obispo, CA

A vector R has x- and y-components as shown at right. The magnitude of vector R is:
(A) 1.9 m.
(B) 2.6 m.
(C) 7.0 m.
(D) 12 m.

Correct answer (highlight to unhide): (B)

The magnitude of vector R is the square root of the sum of the squares of its components R_x = +1.1 m, R_y = –2.4 m:

| R| = sqrt(R_x² + R_y²) = sqrt((+1.1 m)² + (–2.4 m)²)) = 2.640075756 m,

which to two significant figures is 2.6 m.

Response (A) sqrt(|R_x| + |R_y|); response (C) is (R_x² + R_y²); response (D) is (|R_x| + |R_y|)².

Sections 70854, 70855, 73320
Exam code: quiz03eL3v
(A) : 3 students
(B) : 65 students
(C) : 2 students
(D) : 0 students

Success level: 93%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.13