91Ó°ÊÓ

The charge is moving 1000 m/s relative to the Sharon toward left side. Whereas the sharon is moving toward right relative to bill toward right side.

The velcoity of charge relative to the bill is equal to the sum of the velocity of charge relative to the Sharon and the velocity of Sharon reltive to the bill.

$\begin{array}{l}{\stackrel{→}{v}}_{cb}={\stackrel{→}{v}}_{cs}+{\stackrel{→}{v}}_{sb}\\ {\stackrel{→}{v}}_{cb}=1000\text{ }\left(−\text{ â¶ÄŠ}\widehat{i}\right)+1000\text{ â¶ÄŠâ€Š}\widehat{i}\\ {\stackrel{→}{v}}_{cb}=0\end{array}$

Since the velocity of charge is zero.

According to the Lorentz's Force formula $\text{q}({\stackrel{→}{v}}_{cb}×\stackrel{→}{B})$

The net force on the charge is zero.

The charge is moving 1000 m/s relative to the Sharon toward left side.

According to the Lorentz's Force formula$\text{q}({\stackrel{→}{v}}_{cb}×\stackrel{→}{B})$

$\begin{array}{l}\stackrel{→}{F}\text{ â¶ÄŠ= â¶ÄŠq}(\stackrel{→}{v}×\stackrel{→}{B})\\ \text{q}\left[\left(1000\text{ â¶ÄŠm/s}\right)\left(−\text{ â¶ÄŠ}\widehat{i}\right)×\left|\stackrel{→}{B}\right|\left(−\widehat{k}\right)\right]\\ \text{q}\left(1000\text{ â¶ÄŠm/s}\right)\left|\stackrel{→}{B}\right|\text{ â¶ÄŠâ€Š}\left(−j\right)\end{array}$

The magnetic force act in a downward direction.