Answer: Rock require larger drag force and to achieve it rock need to move at a very high terminal velocity.
Explanation: Terminal velocity is defined as the final velocity attained by an object falling under the gravity. At this moment weight is balanced by the air resistance or drag force and body falls with zero acceleration i.e. with a constant velocity.
Case 1: Terminal velocity of a piece of tissue paper.
The weight of tissue paper is very less and it experiences an air resistance while falling downward under the effect of gravity.
Downward gravitational force, F = mg
Upward air resistance or friction or drag force will be 
So, paper will attain terminal velocity when mg =
Case 2: Rock is very heavy and require larger air resistance to balance the weight of rock relative to the tissue paper case.
Downward force on rock, F = Mg
Drag force = 
Rock will attain terminal velocity when Mg =
Mg > mg
so, >
And rock require larger drag force and to achieve it rock need to move at a very high terminal velocity.
Time = (distance) / (speed)
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Time = (450 km) / (100 m/s)
Time = (450,000 m) / (100 m/s)
Time = <em>4500 seconds </em>(that's 75 minutes)
Note:
This is about HALF the speed of the passenger jet you fly in when you go to visit Grandma for Christmas.
If the International Space Station flew at this speed, it would immediately go ker-PLUNK into the ocean.
The speed of the International Space Station in its orbit is more like 3,100 m/s, not 100 m/s.
A hydrogen atom in the n=7 state decays to the n=4 state. The wavelength of the photon that the hydrogen atom emits is 4592.59nm.
The Energy of photon is the energy possessed by a photon when it moves from a high energy level to a low energy level. It emits a photon of a certain wavelength. The following relation can be used to find out the relation between the energy levels and the energy possessed:
E = 13.6 × Z² (1/n₂² - 1/n₁²) eV
where, n₁ is the initial energy level i.e. n₁ =7
n₂ is the higher energy level i.e. n₂ = 4
E is the energy possessed
Z is the atomic number, Z = 1 for H-atom
Subsituting in above equation,
E = 13.6 (1/16 - 1/49) eV
E = 0.27 eV
We know that,
E = hc / λ
where, h is Planck constant
c is speed of light
λ is wavelength
On subsituting,
0.27 eV = 1240/ λ
⇒ λ = 4592.59 nm
Hence, the wavelength of photon emitted by Hydrogen atom is 4592.59nm.
Learn more about Energy of Photon here, brainly.com/question/2393994
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Displacement = 31 - 16 = +15 m
