# How can I challenge a professor who is ignoring me in an online course?

This summer I am taking an online course due to being part of an internship 1000 miles from home. That said, the physics course I am taking the instructor is not grading the tests right. When asked what the right answers are, she responds but then when I ask about the specifics of why I missed them she ignores me.

For example this question,

"An elevator weighing 20 200 N is supported by a steel cable. What is the tension in the cable when the elevator is being accelerated upward at a rate of 3.00 m/s2? (g = 9.80 m/s2)"

She responded that the answer is T = 26383.7 N, then gave me zero points when I wrote 26400 N which seems more correct given significant figures.

Because of this kind of thing my test grade went from a 100 to a C-.

What else can I do?

• Could you please elaborate on the two obtained answers? Is she correct? Or, Are you correct? Who is more close to the answer? Commented Jun 20, 2017 at 16:34
• The instructor's answer is closer to exact. The exact answer is not a terminating decimal fraction, so there is an issue of where to round. Has the instructor either set a policy on rounding, or been reasonably consistent? Commented Jun 20, 2017 at 17:36
• If you write 26400 N, I would interpret that as 5 significant digits. 24.6 kN has 3 significant digits. If you write trailing zeroes, there is no way of knowing if these are part of the significant digits or not. Commented Jun 20, 2017 at 19:25
• @PieterNaaijkens Taking significant digits into account, the data in the problem (3.00 and 9.80), with three significant digits, support the instructor's answer with 6 significant digits even less than the OP's answer. Commented Jun 20, 2017 at 21:32
• @AndreasBlass: yes, that is true, the instructor's answer is even worse in this regard. I suppose it depends on if they were taught to consider significant digits or not. The teacher's answer seems to implie that this has not been discussed (which would be a major omission in my opinion, but ok...). Commented Jun 20, 2017 at 21:39