Question 134: 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: