Answer:

Explanation:
We have given the radius of first sphere is 10 cm and radius of second sphere is 20 cm
So the potential of first sphere will be greater than the potential of the second sphere, so charge will flow from first sphere to second sphere
Let q charge is flow from first sphere to second sphere and then potential become same
So 
200-100=2q+q

So 
We know that potential energy U=qV
Answer:
r= 98.3 mm
Explanation:
For rim
R= 0.209 m
M= 4.32 kg
For rods
m= 7.37 kg
L= 2 R= 2 x 0.209 = 0.418 m
The Total moment of inertia of the wagon
I=MR²+2 x 1/12 m L²
Now by putting the values

I=0.413 kg.m²
For disk:
t= 0.0462 m
Density ρ = 5990 kg/m³
Lets take r is the radius of disk
So the mass of the disc
m'=ρ πr² t
The moment of inertia of disc
I'=1/2 m'r²
I'=1/2 x r² x ρ πr² t
Given that
I = I'
1/2 x r² x ρ πr² t = 0.413 kg.m²
1/2 x r³ x ρ π t = 0.413
r³ x ρ π t = 0.826

r³=0.00095
r=0.0983 m
r= 98.3 mm
Optical Telescopes....................................
<h3><u>Given</u><u>:</u><u>-</u></h3>
Acceleration,a = 3 m/s²
Initial velocity,u = 0 m/s
Final velocity,v = 12 m/s
<h3><u>To</u><u> </u><u>be</u><u> </u><u>calculated:-</u><u> </u></h3>
Calculate the time take by a car.
<h3><u>Solution:-</u><u> </u></h3>
According to the first equation of motion:
v = u + at
★ Substituting the values in the above formula,we get:
⇒ 12 = 0 + 3 × t
⇒ 12 = 3t
⇒ 3t = 12
⇒ t = 12/3
⇒ t = 4 sec
so you can see all the different categories at once. both as a whole and on an individual scale.