The vertical deflecting plates of a typical classroom oscilloscope are a pair of parallel square metal plates carrying equal but opposite charges. The potential difference between the plates is 25.0 V. Typical dimensions are about 4.0 cm on a side, with a separation of about 5.0 mm. The plates are close enough that we can ignore fringing at the ends. Under these conditions:

(a) how much charge is on each plate, and
(b) How strong is the electric field between the plates?
(c) If an electron is ejected at rest from the negative plates, how fast is it moving when it reaches the positive p.

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.