Answer: Ok, first lest see out problem.
It says it's a Long cylindrical charge distribution, So you can ignore the border effects on the ends of the cylinder.
Also by the gauss law we know that E¨*2*pi*r*L = Q/ε0
where Q is the total charge inside our gaussian surface, that will be a cylinder of radius r and heaight L.
So Q= rho*volume= pi*r*r*L*rho
so replacing : E = (1/2)*r*rho/ε0
you may ask, ¿why dont use R on the solution?
since you are calculating the field inside the cylinder, and the charge density is uniform inside of it, you don't see the charge that is outside, and in your calculation actuali doesn't matter how much charge is outside your gaussian surface, so R does not have an effect on the calculation.
R would matter if in the problem they give you the total charge of the cylinder, so when you only have the charge of a smaller r radius cylinder, you will have a relation between r and R that describes how much charge density you are enclosing.
The correct option is D.
Sound proofing is usually achieved by using materials that absorbed or reduce sounds. Different materials are used in sounding proofing and these differ in their abilities to absorb or reduce sounds. The coefficient of absorption of a material refers to that material ability to absorb sound. The higher the percentage of a material absorption coefficient, the better the material's ability to absorb sound. Thus, in the question given above, the material with 62% absorption coefficient have the greatest ability of the three materials to absorb sound effectively. <span />
Most likely the answer is B.
Answer with explanation:
We are given that
Mass of ball,
75 g=
1 kg=1000 g
Height,
Horizontal velocity,
Mass of plate
a.Initial velocity of plate,
Velocity before impact=
Where 
Velocity after impact,
According to law of conservation of momentum
Substitute the values
Velocity of plate=1.69 m/s
b.Initial energy=
Final energy=
Final energy=
Energy lost due to compact=Initial energy-final energy=1.326-1.162=0.164 J
