d = distance between the two point charges = 60 cm = 0.60 m
r = distance of the location of point "a" where the electric field is zero from charge 
between the two charges.
= magnitude of charge on one charge
= magnitude of charge on other charge
= 3
= Electric field by charge at point "a"
= Electric field by charge at point "a"
Electric field by charge at point "a" is given as
= k /r²
Electric field by charge at point "a" is given as
= k /(d-r)²
For the electric field to be zero at point "a"
=
k /(d-r)² = k /r²
/(d-r)² = 3 /r²
1/(0.60 - r)² = 3 /r²
r = 0.38 m
r = 38 cm
(a) Determine the circumference of the Earth through the equation,
C = 2πr
Substituting the known values,
C = 2π(1.50 x 10¹¹ m)
C = 9.424 x 10¹¹ m
Then, divide the answer by time which is given to a year which is equal to 31536000 s.
orbital speed = (9.424 x 10¹¹ m)/31536000 s
orbital speed = 29883.307 m/s
Hence, the orbital speed of the Earth is ~29883.307 m/s.
(b) The mass of the sun is ~1.9891 x 10³⁰ kg.
Answer:
d = 4180.3m
wavelengt of sound is 0.251m
Explanation:
Given that
frequency of the sound is 5920 Hz
v=1485m/s
t=5.63s
let d represent distance from the vessel to the ocean bottom.
an echo travels a distance equivalent to 2d, that is to and fro after it reflects from the obstacle.
wavelengt of sound is 
= v/f
= (1485)/(5920)
= 0.251 m
The distance between a trough and a crest is double the amplitude.
The distance between trough and crest is (9m - 6m) = 3m.
So the amplitude of those water waves is (3/2) = 1.5 meters.
For this question, we really don't need to know how far apart the crests are, or how often they pass. There may be more parts to the question, for which that information is needed.
For example:
-- What's the wavelength of the waves ? 8 meters.
-- What's the period of the waves ? 4 seconds.
-- What's the frequency of the waves ? 1 / (4 seconds) = 0.25 Hz.
-- What's the speed of the waves ? (8 m) x (0.25 Hz) = 2 m/s
