A body is moving with velocity $15 \mathrm{~m} / \mathrm{s}$ towards north. After 5 seconds its velo

Question

A body is moving with velocity $15 \mathrm{~m} / \mathrm{s}$ towards north. After 5 seconds its velocity becomes $20 \mathrm{~m} / \mathrm{s}$ towards east. The magnitude of the average acceleration of the body is

Professor PC Thomas Classes · Answer

(a) : Initial velocity $\vec{v}_1 = 15\hat{j} \mathrm{~m} / \mathrm{s}$. Final velocity $\vec{v}_2 = 20\hat{i} \mathrm{~m} / \mathrm{s}$. \ Change in velocity $\Delta\vec{v} = 20\hat{i} - 15\hat{j}$. \ Magnitude $|\Delta\vec{v}| = \sqrt{20^2 + (-15)^2} = \sqrt{400+225} = 25 \mathrm{~m} / \mathrm{s}$. \ Average acceleration $|\vec{a}_{	ext{av}}| = \frac{|\Delta\vec{v}|}{\Delta t} = \frac{25}{5} = 5 \mathrm{~m} / \mathrm{s}^{2}$.