Answer:
Part a)

Part b)

Explanation:
As we know that capacitor plate is connected across 2.1 V and after charging it is disconnected from the battery
So here we can say that charge on the plates will remain conserved
So we will have

now dielectric is removed between the plates of capacitor
so new potential difference between the plates




Part b)
Now the capacitor plates are again isolated and unknown dielectric is inserted between the plates
So again charge is same so potential difference is given as




In order to compute the final velocity of the trains, we may apply the principle of conservation of momentum which is:
initial momentum = final momentum
m₁v₁ = m₂v₂
The final mass of the trains will be:
10,000 + 10,000 = 20,000 kg
Substituting the values into the equation:
10,000 * 3 = 20,000 * v
v = 1.5 m/s
The final velocity of the trains will be 1.5 m/s
The speed of bullet =
850 m/s
Distance given = 1 km = 1000m
S = D/t
t • S = D/t • t
St = D
St/S = D/S
t = D/S
t = 1000m/850m/s
t = 1.176 s
It will take the bullet 1.176 or about 1.18 seconds to go 1 km.
For the answer to the question above,
the distance from i to j is 5 parts
(2 parts from i to k and 3 parts from k to j)
The y distance from i to j is
10 - 2 = 8
Each part is 8/5 = 1.6
Therefore the distance between the 2 parts from i to k is 3.2
From the y coordinate of I which is 2 plus the 3.2 to point k
2 + 3.2 = 5.2
Answer y =5.2
Now just convert that to fraction and that will be the answer