Solutions:
https://mp.weixin.qq.com/s/YkpKVaNQ63RyEmNzd_vBAA?fbclid=IwAR0MOfM5kqYiQ-svzkkefHF9eYM6bVMjDHdaXHcAujrmtqYBtnPj0c2tw6o
I feel like I must be missing something really simple if I'm wrong, but for multiple choice Question 19, isn't the answer B = 0.06?
\(\begin{aligned}\textrm{Change in momentum }
&= m\left(\vec{v}_f - \vec{v}_i\right) \\
&= 0.02\left(2\vec{i}-7\vec{j} - \left(2\vec{i}-10\vec{j} \right)\right) \\
&= 0.02\left(3\vec{j}\right) \\
\end{aligned} \)
So the magnitude is \(0.02\times 3 = 0.06\).
What, if anything, is wrong with this?
Also, I'm curious to see how Extended Response, Question 4d will be marked, since clearly CAS only gives approximate solutions, whether some additional evidence needed to be given that those are the ONLY solutions for t in [0, 40] (eg. drawing graphs of \(x_a(t)-x_d(t)\) and \(y_a(t)-y_d(t)\) and locating zeroes), and so there is no point of collision.