Answer:
12.1 seconds
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity = 0
s = Displacement = 120 m
a = Acceleration due to gravity on Moon = 1.67 m/s²
Equation of motion


Time taken by the rock to hit the bottom of the crater is 12.1 seconds
Answer:
Imp_{1-2}=5000[kg*m/s]
Explanation:
In order to solve this problem, we must use the principle of conservation of momentum, which is defined as the product of mass by Velocity.
It must be defined that the impulse after the force is applied is equal to the momentum before the impulse applied on the body.
ΣPbefore = ΣPafter
P = momentum = m*v [kg*m/s]
In this way, we will construct the following equation.

where:
m₁ = mass of the object = 200 [kg]
v₁ = velocity of the object before the impulse = 15 [m/s]
v₂ = velocity of the object after the impulse = 40 [m/s]
Now replacing:
![(200*15) + Imp_{1-2} = (200*40)\\Imp_{1-2}=5000[kg*m/s]](https://tex.z-dn.net/?f=%28200%2A15%29%20%2B%20Imp_%7B1-2%7D%20%3D%20%28200%2A40%29%5C%5CImp_%7B1-2%7D%3D5000%5Bkg%2Am%2Fs%5D)
We can solve the problem by using Snell's law, which states

where

is the refractive index of the first medium

is the angle of incidence

is the refractive index of the second medium

is the angle of refraction
In our problem,

(refractive index of air),

and

(refractive index of carbon disulfide), therefore we can re-arrange the previous equation to calculate the angle of refraction:

From which we find