Answer:
θ = 53.13° above horizontal
Explanation:
Ignore air resistance.
The time the ball takes to reach its max height will equal the time to travel half the max range R.
√(2h/g) = (R/2)/vcosθ
vsinθ/g = R/2vcosθ
2v²sinθcosθ = Rg
2v²sinθcosθ = 3hg
v² = u² + 2gh
0² = v²sin²θ + 2gh
v²sin²θ = 2gh
v² = 2gh/sin²θ
2v²sinθcosθ = 3hg
(2gh/sin²θ)2sinθcosθ = 3hg
(2/sinθ)2cosθ = 3
cotθ = 3/4
θ = 53.130
At the position of terminal speed the net acceleration of the ball will become zero
As we know that terminal speed will always reach when net force on the ball is zero and its speed will become constant.
So here at this position we can say



now when ball is moving at half of the terminal speed in upward direction then net force on the ball in downwards direction will be


here speed of the ball is half of the terminal speed

then we have


now acceleration will be given as

now we have

downwards
Answer:
1km = o.621371 mile
Explanation:
1.609 kilometers equal 1 mile. The kilometer is a unit of measurement, as is the mille. However, a mile is longer than a kilometer.
(a) 
The frequency of an electromagnetic wave is given by:

where
is the speed of the wave in a vacuum (speed of light)
is the wavelength
In this problem, we have laser light with wavelength
. Substituting into the formula, we find its frequency:

(b) 427.6 nm
The wavelength of an electromagnetic wave in a medium is given by:

where
is the original wavelength in a vacuum (approximately equal to that in air)
is the index of refraction of the medium
In this problem, we have

n = 1.48 (index of refraction of glass)
Substituting into the formula,

(c) 
The speed of an electromagnetic wave in a medium is

where c is the speed of light in a vacuum and n is the refractive index of the medium.
Since in this problem n=1.48, we find
