Cuesta College, San Luis Obispo, CA
Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 2.11
Two cars are momentarily traveling side-by-side as they both travel in the +x direction at t = 0. Describe/show how the vx(t) graph at right indicates that the cars are not side-by-side at t = 80 s. Explain your reasoning by using the properties of position, displacement, velocity, and acceleration.
Solution and grading rubric:
Correct. Understands that displacement (which here is equal to distance traveled, as there is only straight-line motion in the same direction) is the area of a vx(t) graph, and since the area under car 2 is greater than car 1, then car 2 has traveled a farther distance than car 1 from t = 0 to 80 s, and thus car 2 is ahead of car 1 at t = 80 s.
As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes.
Nearly correct, but argument has conceptual errors, or is incomplete. Some plausible connection made between velocity and distance traveled using kinematic equations for constant acceleration motion and/or integral/differential calculus.
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least some applicaiton of kinematic equations for constant acceleration motion and/or integral/differential calculus, typically focus is on difference of slopes/accelerations.
Implementation/application of ideas, but credit given for effort rather than merit.
Irrelevant discussion/effectively blank.
Sections 70854, 70855
Exam code: midterm01sWFf
p: 16 students
r: 6 students
t: 7 students
v: 28 students
x: 0 students
y: 0 students
z: 0 students
A sample "p" response (from student 1223):
Another sample "p" response (from student 3548), calculating how much car 1 and car 2 have each traveled since they were side-by-side.