As v becomes zero at the highest point, i prefer considering different travelling directions so it will become less complicated.
dont forget to add the total time up .
also to master the skills, write down the "uvsat" may help (thats the way i found it easier to handle problems)
Answer:

Explanation:
As we know that the pressure inside the liquid level is given as

here we have

h = 10.9 km
also we know that

now we have


M1*V1 + M2*V2 = M1*V + M2*V.
1400*25 + 1800*20[180+40]=1400*V+1800*V.
Divide both sides by 100:
14*25 + 18*20[220o] = 14V + 18V.
350 + 360[220o] = 32V.
350 - 276-231i = 32V.
74 - 231i = 32V.
242.6[-72.2o] = 32V.
V = 7.6m/s[-72.2o]=7.6m/s[72o] S. of E.
Answer:the human retina can only detect incident light that falls in waves 400 to 720 nano-meters long so we cant see microwave or ultraviolet wavelengths. this also applies to infrared lights which has wavelengths longer than visible and shorter than microwaves thus being invisible to the human eye
Explanation: