A force \( \vec{F} = (40\hat{i} + 10\hat{j}) \, \text{N} \) acts on a body of mass \( 5 \, \text{kg} \). If the body starts from rest, its position vector \( \vec{r} \) at time \( t = 10 \, \text{s} \), will be:
\( (400\hat{i} + 100\hat{j}) \, \text{m} \)
\( (100\hat{i} + 400\hat{j}) \, \text{m} \)
\( (400\hat{i} + 400\hat{j}) \, \text{m} \)
\( (100\hat{i} + 100\hat{j}) \, \text{m} \)