Question

An electron moving with a velocity of $5\times {10}^{4}m{s}^{-1}$ enters into a uniform electric field and acquires a uniform acceleration of ${10}^{4}m{s}^{-2}$ in the direction of its initial motion. How much distance the electron would cover in $5s$?

• A. $37.5\times {10}^{3}m$
• B. $37.5\times {10}^{4}m$
• C. $30.5\times {10}^{4}m$
• D. $30.5\times {10}^{5}m$

Answer 1

The correct option is B $37.5\times {10}^{4}m$

Given:
initial velocity, $u=5\times {10}^{4}m{s}^{-1}$,
acceleration, $a={10}^{4}m{s}^{-2}$, and
$t=5s$

Using $s=ut+\frac{1}{2}a{t}^2$
$=(5\times {10}^4)\times 5+\frac{1}{2}\left({10}^4\right)\times (5{)}^2=25\times {10}^4+\frac{25}{2}\times {10}^4=37.5\times {10}^{4}m$
= $37.5\times {10}^{4}m$