The initial and final velocities of an object of mass 5 kg are (u = begin{pmatrix} 1 \ 3 end{pmatrix}) and (v = begin{pmatrix} 4 \ 7 end{pmatrix}) respectively. Find the magnitude of its change in momentum.
-
A.
25 -
B.
15 -
C.
(3sqrt{7}) -
D.
(sqrt{10})
Correct Answer: Option A
Explanation
Change in momentum = m (v – u)
= (5 times (begin{pmatrix} 4 \ 7 end{pmatrix} – begin{pmatrix} 1 \ 3 end{pmatrix}))
= (5 times begin{pmatrix} 3 \ 4 end{pmatrix})
= (begin{pmatrix} 15 \ 20 end{pmatrix})
(|m(v – u)| = sqrt{15^{2} + 20^{2}} = sqrt{625} = 25)