Question

The positive vector of a particle is determined by the expression $\overrightarrow{r}=3t^2\hat{i}+4t^2\hat{j}+7\hat{k}$. The distance traversed in first 10 sec is:

• A. 500 m
• B. 300 m
• C. 150 m
• D. 100 m

Answer 1

The correct option is A 500 m

$\overrightarrow{r}=3t^2\hat{i}+4t^2\hat{j}+7\hat{k}$

at $t=10sec$

$\overrightarrow{r}=300\hat{i}+400\hat{j}+7\hat{k}$

Its magnitude is

$r=\sqrt{(300{)}^2+(400{)}^2+(7{)}^2}=500m$

The correct answer is A.