Answer : The energy of one photon of hydrogen atom is, 
Explanation :
First we have to calculate the wavelength of hydrogen atom.
Using Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant = 10973731.6 m⁻¹
= Higher energy level = 3
= Lower energy level = 2
Putting the values, in above equation, we get:


Now we have to calculate the energy.

where,
h = Planck's constant = 
c = speed of light = 
= wavelength = 
Putting the values, in this formula, we get:


Therefore, the energy of one photon of hydrogen atom is, 
Answer:
1.98s
Explanation:
The time taken to hit the ground is given by
h=ut+ 1/2 at^2
but u =0
so we have
h=1/2at^2
making t the subject
t=√2h/g
√2×19.6/10
1.98s
Answer:
17.5 m/s²
1.90476 seconds
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
a = Acceleration
Force

Initial acceleration of the rocket is 17.5 m/s²

Time taken by the rocket to reach 120 km/h is 1.90476 seconds
Change in the velocity of a rocket is given by the Tsiolkovsky rocket equation

where,
= Initial mass of rocket with fuel
= Final mass of rocket without fuel
= Exhaust gas velocity
Hence, the change in velocity increases as the mass decreases which changes the acceleration
Because the frictional force between the orange skin peel is great enough when you are walking for it to be carried on the tray, along with the gravitational force downwards onto the tray. When you stop, the force that you exerted moving forward it the same as on the tray and on the orange. So when you stop, the force is still on the orange as the same velocity as your we’re traveling, while the tray and you stop.
Between magnitude of the average 4sec