I need help with the following word problems.

A capacitor has a charge of +3.0 uC on one plate and a charge of -3.0 uC on the other plate. The potential difference between the plates are 45.0 volts. What is the capacitance of the capacitor if micro farads?

An electron is placed in an electric field between two parallel plates seperated by a distance of 1.00 cm. A potential difference of 1500 volts exists across the plates. What is the force on the electron?

What is the acceleration of the electron?

If the electron starts at rest from the negative plate, with what speed will it strike the positive plate?

Thanks for your help!!

(1)
Capacitance (C) can be related to potential (V) and charge (Q), by the equation:
C = Q ÷ V
For the first question, all you need to do is plug in the values, keeping in mind that the total charge (which is what you need for this equation) is the difference between the charges on each plate (that is, it is 6.0 μC)
Also, keep your units in mind. The way this question is set up, if you plug in the numbers you will get the answer in μF, like you want, but this won't always be the case. Generally, you'll want to convert units to their base unit (centimeters to meters, microcoulombs to coulombs, microfarads to farads, etc.) with mass being the common exception (you'll want that in kilograms) for the calculations and then convert your answer to whatever is asked for at the end.


(2)(a)
Work (W), force (F), and distance (d) can be related by the following:
W = F x d
In terms of an electric field and a particle moving through that field, work can be related to the charge of the particle (Q) and the potential (V) by:
W = Q x V
We can combine the equations, which gets rid of work:
F x d = Q x V
Rearranging to solve for force:
F = Q x V ÷ d
Again, you need to take care with units. It would be best to convert the distance to meters.
1.00 cm x 100 cm ÷ 1 m = 0.0100 m
You'll also need the charge of an electron in Coulombs, which should be in your textbook (it's 1.602 x 10^-19 C).
With that, it's just a matter of plugging everything in, and you should get force in Newtons.

(b)
Acceleration (a) can be related to force (F) and mass (m) by the equation:
F = m x a
which can be rearranged as:
a = F ÷ m
From the last part, you should know know the force, and you can look up the mass of an electron (or trust me that it's 9.109 x 10^-31 kg)

(c)
Acceleration (a), distance (d), time (t),and velocity (v) can be related through a lot of different equations. They're all really versions of the same equation, and the key is to find the one that has only the values you know and the value you want to know.
You know the initial velocity (v(0) = zero), the acceleration (from the last part), and the distance (0.0100 m), so the equation you want is:
v^2 = v(0)^2 + 2 x a x d
or
v = square root [v(0)^2 + 2 x a x d]
If you've kept your units straight, this will give you your answer in meters per second.