Answer:
Chinese app which is number
Explanation:
Given: Mass of Mars Mm = 6.24 x 10²³ Kg;
Mass of Phobos Mp = 9.2 x 10¹⁵ Kg
Gravitational Force F = 4.47 X 10¹⁵ N
Gravitational constant G = 6.67 X 10⁻¹¹ N m²/Kg²
Radius r = ?
Formula: F = GMmMp/r² derive r
r = √GMmMp/F
r = √(6.67 x 10⁻¹¹ N m²/Kg²)(6.24 x 10²³ Kg)(9.2 x 10¹⁵ Kg)/4.47 x 10¹⁵ N
r = √(6.67 x 10⁻¹¹ N m²/Kg²)5.74 x 10³⁹ Kg²/4.47 x 10¹⁵ N
r = √8.57 x 10¹³ m
r = 9,257,429 m
or r = 9.26 x 10⁶ m
(a) 
First of all, we need to calculate the acceleration of the person, by using the following SUVAT equation:

where
v = 0 is the final velocity
u = 20.0 m/s is the initial velocity
a is the acceleration
d = 1.00 cm = 0.01 m is the displacement of the person
Solving for a,

And the average force on the person is given by

with m = 75.0 kg being the mass of the person. Substituting,

where the negative sign means the force is opposite to the direction of motion of the person.
b) 
In this case,
v = 0 is the final velocity
u = 20.0 m/s is the initial velocity
a is the acceleration
d = 15.00 cm = 0.15 m is the displacement of the person with the air bag
So the acceleration is

So the average force on the person is

Answer:
f = 1.5 x 10¹⁵ Hz
Explanation:
Light is an electromagnetic wave and we know that the speed of light is a constant which is
3 x 10⁸ m/s.
Knowing this; v = λ x f
λ = wavelength
f= frequency of light
v = seed of light
f = v/λ
f = 3 x 10⁸m/s / 2.0 x 10-⁷ m
f = 1.5 x 10¹⁵ Hz