Question:
A cricket ball of mass $150 \mathrm{~g}$ has an initial velocity $u=(3 \hat{i}+4 \hat{j}) \mathrm{m} / \mathrm{s}$ and a final velocity $v=-(3 \hat{i}+4 \hat{j}) \mathrm{m} / \mathrm{s}$ after being hit. The change in momentum
(a) zero
(b) $-(0.45 \hat{i}+0.6 \hat{j})$
(c) $-(0.9 \hat{i}+1.2 \hat{j})$
(d) $-5(\hat{i}+\hat{j})$
Solution:
The correct answer is $\mathrm({c})-(0.9 \hat{i}+1.2 \hat{j})$