The initial velocity of an object is (u = begin{pmatrix} -5 \ 3 end{pmatrix} ms^{-1}). If the acceleration of the object is (a = begin{pmatrix} 3 \ -4 end{pmatrix} ms^{-2}) and it moved for 3 seconds, find the final velocity.
-
A.
(begin{pmatrix} -14 \ 15 end{pmatrix} ms^{-1}) -
B.
(begin{pmatrix} -2 \ 1 end{pmatrix} ms^{-1}) -
C.
(begin{pmatrix} 4 \ -9 end{pmatrix} ms^{-1}) -
D.
(begin{pmatrix} 14 \ -9 end{pmatrix} ms^{-1})
Correct Answer: Option C
Explanation
(u = begin{pmatrix} -5 \ 3 end{pmatrix} ms^{-1})
(a = begin{pmatrix} 3 \ -4 end{pmatrix} ms^{-2}; t = 3 secs)
(v = u + at implies v = begin{pmatrix} -5 \ 3 end{pmatrix} + begin{pmatrix} 3 \ -4 end{pmatrix} times 3)
= (begin{pmatrix} -5 \ 3 end{pmatrix} + begin{pmatrix} 9 \ -12 end{pmatrix} = begin{pmatrix} 4 \ -9 end{pmatrix} ms^{-1}))