<span>Work: W = Fd. 50(distance) multiplied by 90(force) would equal 4500 J or, answer D</span>
Answer:

Explanation:
The mass of one electron is

So the number of electrons contained in M=1.7 kg of mass is

The charge of one electron is

So, the total charge of these electrons is equal to the charge of one electron times the number of electrons:

Answer:
Energy density will be 14.73 
Explanation:
We have given capacitance 
Potential difference between the plates = 365 V
Plate separation d = 0.200 mm 
We know that there is relation between electric field and potential
, here E is electric field, V is potential and d is separation between the plates
So 
Energy density is given by
Answer:
t = 3 seconds
Explanation:
Given that,
Initial speed, u = 30 m/s
Final speed, v = 0
It slides 45 m to rest.it take the box to come to rest
We need to find how long it take the box to come to rest.
Let a be the acceleration and t is time.

Now finding time.

So, the required time is 3 seconds.