Expand each vector into their component forms:

Similarly,


Then assuming the resultant vector
is the sum of these three vectors, we have


and so
has magnitude

and direction
such that

Answer:
1408.685 KN/C
Explanation:
Given:
R = 0.45 m
σ = 175 μC/m²
P is located a distance a = 0.75 m
k = 8.99*10^9
- The Electric Field Strength E of a uniformly solid disk of charge at distance a perpendicular to disk is given by:

part a)
Electric Field strength at point P: a = 0.75 m

part b)
Since, R >> a, we can approximate a / R = 0 ,
Hence, E simplified relation becomes:

E = σ / 2*e_o
part c)
Since, a >> R, we can approximate. that the uniform disc of charge becomes a single point charge:
Electric Field strength due to point charge is:
E = k*δ*pi*R^2 / a^2
Since, R << a, Surface area = δ*pi
Hence,
E = (k*δ*pi/a^2)
Answer:Reflection
Explanation:
The throwing back of a sound wave without absorbing it is called reflection
In acoustic reflection of sound is termed as echo i.e. sound arrived at the listener after a particular delay depending upon the position of barrier to the observer.
The reflection of sound is used in many devices like megaphone, trumpets, etc. It is also used in auditorium such that the ceiling of the auditorium is curved for multiple reflections of sound so that sound can be reached at every corner of the auditorium.
The average force applied to the ball= 106.7 N
Explanation:
Force is given by
f= ΔP/t
ΔP= change in momentum= m Vf- m Vi
m= mass =0.2 kg
Vf= final velocity= 12 m/s
Vi=initial velocity= -20 m/s ( negative because it is going towards the wall which is treated as negative axis)
t= time= 60 ms= 0.06 s
now ΔP= 0.2 [ 12-(-20)]
ΔP=0.2 (32)=6.4 kg m/s
now force F= ΔP/t
F= 6.4/0.06
F=106.7 N