Question 139: Motion in 2D & Vectors

Question

A particle has an initial velocity $3\widehat i + 4\widehat j$ and an acceleration of $0.4\widehat i + 0.3\widehat j$. Its speed after 10 s is:

Accepted Answer

Given $\overrightarrow u  = 3\widehat i + 4\widehat j,\,\,\overrightarrow a  = 0.4\widehat i + 0.3\widehat j,\,\,t = 10s$
$\overrightarrow v  = \overrightarrow u  + \overrightarrow a t $
$= 3\widehat i + 4\widehat j + \left( {0.4\widehat i + 0.3\widehat j} ight) 	imes 10$
$ = 7\widehat i + 7\widehat j$
We know speed is equal to magnitude of velocity.
$	herefore$ $\left| {\overrightarrow v } ight| = \sqrt {{7^2} + {7^2}}  = 7\sqrt 2 \,\,\,$  units

Answer

$7\sqrt 2 $ units

Answer

7 units

Answer

8.5 units

Answer

10 units

Motion in 2D & Vectors

A particle has an initial velocity 3\widehat i + 4\widehat j and an acceleration of 0.4\widehat i + 0.3\widehat j. Its speed after 10 s is:

Choose the correct answer: