5 ft/s is an incredibly slow run. My boy is fake sprinting away while actually going at a slow walking pace.
And 1ft/sec is practically an impossible speed to walk at, she’s like gone so insane she’s pigeon-stepping away.
Because its DiffEq, I’m assuming these were intended to be accelerations rather than velocities. So, he starts walking away and then picks up into a sprint. She starts at a crawl and advances to a steady walk.
But I bet the person writing the prompt (or the app translating the question) fumbled the notation for s^2, so now (hopefully) the entire class is going to fail this question and get it curved out.
Agreed. But even then, who the hell walks away from a point with linear acceleration? That’s really hard to picture.
fucking calculus :homer-bye:
You can solve this without a single differentiation or integration. This is barely algebra.
Okay so by the Pythagorean theorem, a^2 + b^2 = c^2
If we take the boy’s position at time t as a, then a = 5t, and the girl’s position b = t
Thus their distance at a given time is sqrt((5t)^2 + t^2) = sqrt(26t^2) =sqrt(26)t
Taking the derivative of that in terms of t gives us sqrt(26) feet
I think, it’s been like 10 years since I last studied calculus
yeah ur right. but the rate of change of the distance between them is always sqrt(26) ft/s. the problem is flawed since it doenst actually require calculus to solve, just plug in t=1 and you get sqrt(26)
the problem is flawed
I hate questions that have this confusing language element (rate of separating… after 5 seconds) when it isn’t even clear if the person writing the question knew what they were asking. You’re left second-guessing the test-prompt, because now you’re double checking to see if the original 5 ft/s, 1 ft/s were actually accelerations rather than velocities. You’re worried that the answer is too easy, because it doesn’t involve the math you were prompted to study prior to the exam. You’re wasting time on parsing the language rather than doing the math.
Its just an awful way to conduct an exam, because its rewarding confidence rather than competence.
I mean, precisely. It’s Pythagoras and linear algebra, this is not calculus.
Huh? You took the derivative by taking ‘t’ off the end, that ain’t calculus.
As a math guy, the answer is that he’s not going to move on for a while, while she already has.
A: a million miles, too many to ever return
