Cuesta College, San Luis Obispo, CA
Cf. Giambattista/Richardson/Richardson, Physics, 1/e, Chapter 4.1
Students were asked the following clicker questions (Classroom Performance System, einstruction.com) near the beginning of their learning cycle:
Two forces act on an object, as shown below.
[0.6 participation points.] The horizontal component of the net force acting on the object is _____ N.
[0.6 participation points.] The vertical component of the net force acting on the object is _____ N.
Correct answers: F_net,x = 5 N, F_net,y = -2 N.
Student responses (open-ended numerical responses, unpaired)
Sections 0906, 0907
F_net,x = 4 N: 2 students
F_net,x = 5 N: 37 students
F_net,x = 30 N: 1 student
F_net,y = -18 N: 1 student
F_net,y = -3 N: 2 students
F_net,y = -2 N: 35 students
F_net,y = 2 N: 1 student
Two forces act on an object, as shown below.
[0.6 participation points.] The horizontal component of the net force acting on the object is _____ N.
[0.6 participation points.] The vertical component of the net force acting on the object is _____ N.
Correct answers: F_net,x = 8 N, F_net,y = 3 N.
Student responses (open-ended numerical responses, unpaired)
Sections 0906, 0907
F_net,x = 4 N: 21 students
F_net,x = 6 N: 2 students
F_net,x = 8 N: 15 students
F_net,y = 0.03 N: 1 student
F_net,y = 0.75 N: 1 student
F_net,y = 1.5 N: 1 student
F_net,y = 2 N: 1 student
F_net,y = 3 N: 32 students
F_net,y = 4 N: 1 student
F_net,y = 8 N: 1 student
When orthogonal forces are drawn tail-to-tail, students are relatively successful in summing horizontal and vertical components of the net force. However, the second example demonstrates students having difficulty with vector addition, apparently because they are "completing the triangle" to find the resulting net force.
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