An electron's position is given by r = 4.00t i - 6.00t2 j + 5.00 k, with t in seconds and r in meters.
(a) In unit-vector notation, what is the electron's velocity v(t)? (Answer in terms of i, j, k, and t.)
(b) What is v in unit-vector notation at t = 8.00 s?
(c) What is the magnitude of v at t = 8.00 s?
(d) What angle does v make with the positive direction of the x axis at t = 8.00 s?
___ ° (from the +x axis)
..for (a), i got:
and for (b):
what am i doing wrong?