Question

A man is moving downward on an inclined plane with a constant velocity v° and rain drops appear to him moving in horizontal direction with velocity 2v°. Please open the attached picture for further details.

Answer 1

This question is based on relative concepts of rain and main.
Let $\bf{v_{mg}= v_m}$is relative velocity of man with respect to ground.
$\bf{v_{rg}=v_r}$ is the relative velocity of rain with respect to ground.
And $\bf{v_{rm}}$ is the relative velocity of rain with respect to man.
Relation between $\bf{v_m,v_r\:and\:v_{rm}}$ is $\bf{v_{rm}=v_r-v_m}$ 

Given,
$\bf{v_m}$= v₀cos37°(-i) + v₀sin37°(j) 
$\bf{v_m}$ = -4v₀/5 i + 3v₀/5 j 
and $\bf{v_{rm}}$ = 2v₀ i 
Hence, $\bf{v_{rm}=v_r-v_m}$
$\bf{v_r}$ =2v₀i +(-4v₀/5 i + 3v₀/5 j) 
= 6v₀/5 i + 3v₀/5 j ----(1)

Now, velocity of man with respect to ground, $\bf{v_m}$​ = -2v₀cos37° i + 2v₀sin37°j 
= -8v₀/5 i + 6v₀/5 j 
$\bf{v_{rm}}$​ = 6v₀/5 i + 3v₀/5 j -(- 8v₀/5 i + 6v₀/5 j)
= 14v₀/5 i - 3v₀/5 j
Now, |$\bf{v_{rm}}$ | = √{(196 + 9)/25}v₀ = √{205/25}v₀ =√(41/5)v₀
Hence, n =41

Answer 2

Answer:

Answer is 46

Explanation: