Magnetic force of a falling ball

[mba444]

Homework Statement

A metal ball having net charge 4.5 × 10−6 C
is thrown out of a window horizontally at a
speed 43 m/s. The window is at a height
63 m above the ground. A uniform horizon-
tal magnetic field of magnitude 0.071 T is
perpendicular to the plane of the ball’s tra-
jectory.
The acceleration of gravity is 9.8 m/s2 .
Find the magnitude of the magnetic force
acting on the ball just before it hits the
ground. Answer in units of N.

Homework Equations

F=QVB
V=sqrt(2*g*H)

The Attempt at a Solution

i enterd the given values and solved for v and then re-enterd the answer in the force equation but my final solution is wrong don't why .. can somone explain were I am going wrong

thanx

 

[Doc Al]

V=sqrt(2*g*H)

This gives the vertical component of velocity, but don't forget about the horizontal component. (In the force equation, you need the total velocity.)

 

[mba444]

which is the initial velocity given in the equation

 

[mba444]

what i did
is that i added the Vo + sqrt(2gh) .. then i multilpied it by the charge and the nagnetic field

is that what you meant !

 

[mba444]

finish i figured it out thanks alot